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The Ideal End: Aping the format of VH1's Behind the Music, the ''Behind the Laughter'' episode brilliantly portrayed the true story of The Simpsons: they're all actors playing themselves. It's a brilliant parody of the rise-and-fall-and-rise celebrity narrative, and features a nonstop array of one-liners. ''The dream was over. Coming up: Was the dream really over? Yes it was. Or was it?''
Badness Avoided: Yes, it was. There are plenty of bright spots in The Simpsons' second decade, but the show has never really rediscovered its '90s mojo. You can trace the problems right to this episode: Once you go meta, it's hard to go back. —Darren Franich
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The Ideal End: Not every show can reinvent itself and still hang in there like Weeds. Throughout its run, Nancy Botwin burned down suburbs, traversed borders, and served time. But as the question changed from how she would escape her latest mess to why she was still in it at all, the time had come to call it quits. The end of season 6 was the perfect window: In a thrilling finale, Nancy escaped death and protected her family by turning herself in at the last minute.
Badness Avoided: The season 6 finale made up for an aimless plot that followed the fugitive Botwins on the run. Though season 7 was an improvement, largely because the show returned to some of its roots — drug gang rivalries, Heylia's return — Nancy became harder to root for, and the plot twists were too easily resolved. —Nolan Feeney
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The Ideal End: ''Landslide,'' the penultimate episode of the first season, ends with the villainous Sylar looking out on New York, testing his newly-acquired radiation powers. With a smile of expectant triumph on his face, he says, ''Boom.'' It's a thrilling vision of evil triumphant, and a perfect encapsulation of everything Heroes did so well?for one season.
Badness Avoided: The disappointingly anticlimactic season finale, three seasons of steadily diminishing returns, an uncountable number of plotlines centering on power drains and/or amnesia, the infinite repetition of the phrase ''Claire Bear,'' the regression of Hiro into a man-child, and the never-ending ''Evil Circus'' season 4 story arc. —Darren Franich
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The Ideal End: The fourth episode of season 6 ends with a pair of unexpected disasters. First, Kiefer Sutherland's Jack Bauer is forced to kill one of his most trusted friends to save a terrorist. Mere minutes later, Bauer witnesses a nuclear bomb go off in Valencia. The look on Bauer's face as he stares up at the mushroom cloud is unforgettable.
Badness Avoided: The utterly forgettable season that followed (oh no, evil grandpa!), the failed moves to D.C. and Manhattan, the Renee era, the Dana fiasco, the wimpy series finale, and the Live Another Day revival. Turns out that Curtis was the glue holding 24 together. Who knew? —Darren Franich
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The Ideal End: The season 6 finale, written by married showrunners Amy Sherman-Palladino and Daniel Palladino, in which Lorelai winds up in bed with baby-daddy Christopher.
Badness Avoided: The showrunners' departure turned the show into a bad waxwork imitation of itself in the lunatic last season. Sometimes, it's better to end on a cliffhanger than a long, slow descent. —Darren Franich
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The Ideal End: The show was already past its prime in season 7 — remember the ''virtual reality'' episode where Mulder and Scully play a low-budget Matrix? — but that season finale brought the story back to the beginning, with Mulder and Scully returning to the site of their first case. In a final Shakespeare-tragic twist, alien-obsessed Mulder is abducted.
Badness Avoided: The mostly Duchovny-less final two seasons, the steadily dawning awareness that the central conspiracy made no sense whatsoever, Gillian Anderson's increasingly bored portrayal of Scully, the failed attempt to replace the iconic pair with Robert Patrick (who was actually pretty fun on the show) and Annabeth Gish (who wasn't), and the series finale, which proves — along with Seinfeld — that you really shouldn't end your series by putting your characters on trial. —Darren Franich
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The Ideal End: The Speidi Wedding episode, featuring the last appearance of Lauren Conrad. The scene where LC and Heidi share a brief conversation before the wedding is inexplicably moving, despite (or perhaps because of) the show's confusing cocktail of fantasy and reality.
Badness Avoided: The abandonment of even the most tenuous link to reality, the simultaneous abandonment of any interesting dramatic tension, the never-as-fun-as-she-could-have-been presence of bad girl Kristin, the questionable choice to make the central plotline of the show's final season ''I think I'm in love with Justin Bobby and/or Brody Jenner,'' the freak-show descent of Spencer and Heidi, and the existence of Ryan Cabrera.
Then Again? The show's ending was a brilliant meta-twist, arguably the most intelligent thing The Hills ever did. —Darren Franich
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The Ideal End: You could make the argument that Scrubs should have ended at several points in its run; especially in the later seasons, the show's unwieldy mix of tones could veer into cartoonish farce. But when Scrubs jumped to ABC for its eighth (and supposedly last) season, it rediscovered the magic. Not too many people were watching, but the eighth season finale is a near-perfect distillation of everything that made the show wonderful.
Badness Avoided: Season 9, in which most of the main cast members stuck around just long enough to collect one last paycheck before making way for a new cast of blandroids. —Darren Franich
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My Name Is Earl
The Ideal End: In the season 2 finale, Earl sacrifices himself to rescue ex-wife Joy from prison. The judge rewards him for this selflessness with a two-year sentence.
Badness Avoided: It's always admirable when TV shows try to shake up their format. Unfortunately, My Name is Earl simply went too far. Twice! First, Earl spent the first half of season 3 in prison, a setting that killed the show's jokey momentum. Then, after finally getting out, he was run over by a car and sent to a bizarre sitcom coma-dreamworld. First prison, then a coma...oh, Earl, we missed the old you. —Darren Franich
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The Ideal End: Serialized nail-biters don't get much better than Prison Break's first season, which extended a movie-ready story line with nonstop plot twists and juicy atmospheric touches (like protagonist Michael Scofield's full-body tattoo). The first season finale followed through on the inherent promise of the title...
Badness Avoided: ...and nothing was ever the same. Without the prison setting, season 2 was just a confusing cross-country tour. (The series creator referred to it as ''The Fugitive times eight,'' which it turns out is exactly as bad as it sounds.) Season 3 tried to recapture the magic by sending practically the entire cast back to prison...this time, in Panama. (Oooo, how foreign!) So, just to recap: My Name Is Earl should have never gone to prison, and Prison Break should have never left. —Darren Franich
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The Ideal End: Season 4 of The Wire is a smart-money pick for single greatest sustained achievement in TV history. Moving onward and upward from cops and criminals, the show crosscut between the travails of a group of middle-schoolers, the expanding power of the Marlo Stanfield gang, and the heavy-duty politicking of the Baltimore mayoral election.
Badness Avoided: Don't get us wrong: season 5 of The Wire is still vivid and incisive. But the central conflict of the season — the battle for the soul of the Baltimore Sun — felt oddly paint-by-numbers, with upstanding ''real'' journalists battling soulless glamourpuss editors. Also not helping matters: an uninvolving plotline about a fake serial killer, and the shortened episode run: 10 episodes, down from 13 for the first four seasons. —Darren Franich
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The Ideal End: The first two seasons of Veronica Mars successfully followed one overarching story line through a relentless array of single-episode mysteries — a difficult mix, as every failed serialized show can attest. Funny, sad, and thrilling, Veronica Mars is also an achingly recognizable portrait of high school life. Simply put, this was the best show UPN ever broadcast. And then season 3 started.
Badness Avoided: There's no way to get around it: college ruins all high school shows. (Sorry, Glee, you should've seen it coming.) Mars also wasn't helped by the decision to change the format from a season-long story line to tiny multi-episode mystery arcs. —Darren Franich
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The Ideal End: Immediately before the final scene of the season 9 premiere. The episode feels a little bit like a series finale already: after a big fight, Roseanne imagines herself and husband Dan as couples from old sitcoms like I Dream of Jeannie and The Mary Tyler Moore show. (There's even a cameo by Ed Asner as Lou Grant.) In the end, they reconcile...
Badness Avoided: But in the very end, the family wins $108 million in the lottery. It was a risky gambit for a show grounded in a blue-collar setting...and it didn't pay off. A season of unfun hysteria ended with a mind-imploding revelation that the final season, and perhaps most of the show's run, was actually all part of Roseanne's fictionalized portrayal of her own life. —Darren Franich
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The Ideal End: The season 1 finale concluded the show's masterful ''Mel Profitt'' story arc, featuring Kevin Spacey in a legendary performance as a brilliant, heroin-addicted arms dealer with a deeply unhealthy fixation on his sister.
Badness Avoided: Wiseguy was never as good after Spacey's exit from the series. —Darren Franich
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Studio 60 on the Sunset Strip
The Ideal End: The series premiere. Few pilots have ever been this good: fast, funny, full of ideas and great acting.
Badness Avoided: Everything else. Few shows have gone downhill so fast. You could argue that Studio 60's weird mix of inside-Hollywood snark and big-thought philosophizing was bound to get old fast, especially compared to the much zippier, actually funny 30 Rock, which debuted the same season. —Darren Franich
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The Ideal End: The season 2 finale. Someday, when future generations are trying to understand Hollywood in the mid-'00s, they'll look to the second season of Entourage, which hilariously sent up the Era of the Superhero Movie with an incisive exploration of the making of James Cameron's Aquaman. Plus, trips to Sundance and to Comic-Con!
Badness Avoided: Two seasons spent in the Medellín quagmire, the curious decision to keep bringing back Sloan, an eternity of Turtle doing nothing, and a never-ending parade of celebrity guest stars. (Jamie-Lynn Sigler: You're no Mandy Moore.) Entourage never achieved the comic-decadent perfection of season 2. —Darren Franich
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21 Jump Street
The Ideal End: The season four finale, in which the undercover cops find themselves trapped in school during a blackout. Blackout episodes are practically guaranteed to be awesome, whether in comedy (Friends, Frasier) or drama (Gossip Girl, Kings.) More to the point, this was the last episode to feature series star Johnny Depp.
Badness Avoided: 21 Jump Street never recovered. Depp ended up doing okay, we hear. —Darren Franich
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The Ideal End: Producer Ryan Murphy specializes in over-the-top TV. His shows are a purposefully insane mishmash of genres, which means they're often very good...until they go bananas. The Nip/Tuck season 2 finale is miles over-the-top in the best way: suicide, a great WTF twist (she used to be a he!) and a guest-starring performance by Joan Rivers.
Badness Avoided: Nip/Tuck never stopped being as crazy as it could be, but the maniac plot twists eventually just felt repetitive. —Darren Franich
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The Ideal End: Friends started and ended with Ross and Rachel, but the series really hit its stride in the middle, with the Monica-Chandler relationship. The two-part season 7 finale featured the couple's wedding. Dare you not to cry tears of joy when A Groovy Kind of Love starts playing.
Badness Avoided: Marriage and pregnancy are beautiful things in real life. Why, oh why, do they insist on killing our favorite shows? Also, Joey fell for Rachel, which used to be the ickiest romance ever before Grey's Anatomy's Gizzie. —Darren Franich
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The Ideal End: For a show about rich kids with problems, The OC's first season was surprisingly epic: by turns funny and soap-opera tragic. (The OC also created the curious coalition of high school brains, indie music fanboys, and comic book geeks.) The season 1 finale is fantastic: the Caleb-Julie marriage magically makes every character a distant relative of everyone else, and Jeff Buckley's rendition of ''Hallelujah'' was never used better. (Sorry, West Wing, ER, Ugly Betty, Scrubs, and so many more.)
Badness Avoided: A parade of dull new characters, a shameless lesbian flirtation, an embarrassingly overwrought detour into the California public school system, Sandy Cohen's endless season 3 journey to the dark side, a series of poor decisions by Marissa Cooper, and the queasy feeling that The OC was becoming the show haters always said it was.
Then Again... Not all the new characters were bad: Autumn Reeser's Taylor Townsend was a manic breath of fresh air. And the Taylor-ific, Marissa-free season 4 regained the show's fizzy spirit. Even the music got good again. —Darren Franich
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Happy Days and That 70s Show
The Ideal End: What do these two shows have in common? Both were drenched in nostalgia: one was a '70s show about the '50s, and one was a '90s show about the '70s. Both featured a cast of teenagers. Both were tasty sitcom treats in their prime. And both should have lasted exactly half as long as they did.
Badness Avoided: The departure of both show's main characters (Ron Howard and Topher Grace both left after their seventh seasons), the disquieting temporal inertia (just how much longer will this decade last?) and the simple truism that nostalgia is only fun until it becomes annoying. —Darren Franich
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The Ideal End: The season 9 premiere makes it personal: Gary Dourdan's Warrick Brown, one of the show's original characters, is murdered, and his fellow CSIs track down his killer. It's rare for a procedural show to come up with such an emotional hour of television, almost a decade into its run.
Badness Avoided: Later that season, William Petersen's Gil Grissom departed. Initial replacement Laurence Fishburne couldn't match Petersen's gravitas. Ted Danson is doing his best, but since the exit of original cast member Marg Helgenburger, CSI feels more like a CSI spin-off every year. —Darren Franich
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Six Feet Under
The Ideal End: The undertaker series could be numbingly depressing, but there was no doubting the emotion in the season 3 finale, in which matriarch Ruth remarried and someone unexpectedly turned up dead.
Badness Avoided: Two seasons of moping and increasingly zany emotional battering.
Then Again... The utterly unique series finale is, if nothing else, the best use of old-age makeup since Little Big Man. —Darren Franich
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The Ideal End: ''Niagara.'' Because even in the great pantheon of wonderful sitcom wedding episodes, there's something extra-special about The Office's. Maybe it's because they worked in two weddings for the price of one: the amusing all-cast re-enactment of the viral ''JK Wedding Entrance Dance'' video, and the dare-you-not-cry shipboard marriage of Jim and Pam underneath Niagara Falls.
Badness Avoided: The rest of The Office's sixth season felt a bit like a letdown, and the long goodbye of Michael Scott felt like a victory lap for a series with its best days long behind it. And then it kept going for one more season. —Darren Franich