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David Cook (season 7, winner)
Sure, David Cook totally rocked Bon Jovi's ''Living on a Prayer'' in his audition, but it was hard to concentrate on his singing with what looked like a rooster sitting on top of his head. And that argyle sweater. No. Just no. His style screamed poser, but that would change at one pivotal moment during the finals: when Cook debuted his New Hair on top 9 Country Night. Goodbye, bad comb-over. Hello, hotness! Once again, concentrating on his exquisite cover of Dolly Parton's ''Little Sparrow'' was tough—but this time for all the right reasons.
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Clay Aiken (season 2, runner-up)
''I'm the American Idol,'' declared Clay Aiken at his initial audition in front of the judges. That pronouncement was hard to believe considering the special-education instructor's baggy, unflattering clothes and a short 'do that accentuated his Alfred E. Newman-like ears. Clay's geek-to-chic style makeover included a flattering ear-minimizing haircut and a fashionable wardrobe that not only matched his pop-star pipes, but literally had the ladies swooning.
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Katharine McPhee (season 5, runner-up)
Ill-fitting clothes and thin, stringy looking hair mattered not when Katharine McPhee sang a soulful and sweet ''God Bless the Child'' for the judges at her San Francisco audition. But by the time Kat hit the finale with Taylor Hicks, she had slimmed down and glammed up into the Smash babe we now know and love.
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Kimberley Locke (season 2, third place)
Kimberly Locke, with her geeky glasses and mop of unruly hair, looked every bit the future law-school student she was at her audition. By the time she was eliminated in third place, her hair was straightened and the glasses were gone—revealing some super classic cheekbones. Who knew the girl was so pretty? She could sing her face off but we really didn't want her to.
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Adam Lambert (season 8, runner-up)
Adam Lambert was stylish from the minute he walked into his San Diego audition in skinny jeans and simple layered top and black jacket. Eventually he would rock the black nail polish, fingerless gloves, platform-boots and studded jackets. The outfits could be outrageous, but always uniquely Adam.
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Kelly Clarkson (season 1, winner)
Kelly Clarkson was cute as ever in her audition, but what the heck was that tie-dyed top she was wearing? The rip in the back looked like she caught it on something. With a little styling, Kelly was both cute and chic.
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Elliott Yamin (season 5, third place)
Elliott first appeared on Idol in scruffy clothes and a short, unflattering haircut. While it was his soulful tenor that mattered, he became a bonafide Idol when he grew his hair out and upgraded his wardrobe. When the dude cleaned up, he became downright handsome.
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Lauren Alaina (season 10, runner-up)
Country cutie Lauren Alaina turned into the Amazing Shrinking Teen as she lost 16 pounds during the course of the season. By the time she came in second place to fellow country teen Scotty McCreery, Lauren was looking good in sleek ensembles and signature boots.
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Taylor Hicks (season 5, winner)
Are you someone's dad? That was the question on everyone's lips when gray-haired Taylor Hicks auditioned for Idol. His shapeless short-sleeved shirt screamed ''I'm off to the lanes with my buds!'' The soul man eventually succumbed to a decent haircut and some spiffy duds but refused a dye job. A shrewd move, as the combination of his salt-and-pepper locks and throwback style made him a hit with the older set, propelling him past front-runner Chris Daughtry for the win.
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Carrie Underwood (season 4, winner)
Carrie Underwood was 100 percent wholesome milkmaid when she auditioned for Idol in a pink T-shirt and curly blond hair. The former farm girl would eventually rock some pretty sexy looks by the time she stood center stage in tears as she took the crown—foreshadowing her future as a country superstar and style icon.
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Haley Reinhart (season 10, third place)
Haley Reinhart began her season 10 journey as a retro hippie-chick in Milwaukee, but by the time she was eliminated in third place, she had adopted a sexier and sleeker style. Her newly glamorous look was a perfect complement to the soulful chanteuse's jazz-infused vocals.
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Jon Peter Lewis (season 3, eighth place)
Dubbed the Pen Salesman by Simon Cowell when he walked into his Hawaii audition dressed in his Sunday best: a short-sleeved dress shirt and tie. By the time the finals began, JPL left the Mormon Missionary look behind for vintage velvet jackets and fashionable jeans.
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Melinda Doolittle (season 6, third place)
The unassuming background singer with the big voice arrived at her audition in a cute hat, jeans, and vest ensemble. Although Melinda upgraded her look for Idol, she told Ryan Seacrest in a sit down that ''the high heels and these dresses'' were the hardest part of the show. ''I like my tennis shoes and my sweatpants!'' declared Melinda.
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Lee DeWyze (season 9, winner)
Lee DeWyze, a dude who never met a beanie he didn't like, dressed simply for his Chicago audition in a black T-shirt and jeans. Eventually the indie rocker incorporated leather and suit jackets with loose ties into his wardrobe—a relaxed yet fashionable look for the eventual Idol winner.
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Crystal Bowersox (season 9, runner-up)
Crystal Bowersox never lost the hippie-chick vibe she walked into her Chicago audition with, but she did dress up her look with vintage jewelry and handsome ensembles that featured long dark jackets and pants. She even wore long funky dresses and occasionally wore her dreads up—a look that was funky, but chic.
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Casey Abrams (season 10, fifth place)
He didn't want to trim his bushy red beard, but after being brought back from the abyss by the judges' save at top 11, Casey finally realized that sporting a look that was possibly scaring small children was not the way to stay in the competition. He came back the following week with neatly trimmed hair and beard, helping the jazz man stick around a little longer.
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Haley Scarnato (season 6, eighth place)
Haley Scarnato favored long glamorous dresses when she first strutted the Idol stage, but after she hit the bottom 3, she ditched the skirts for short shorts that showed off those long, long legs. The guys didn't mind at all, and it might have helped the former gymnast to make it as far as she did, despite bad critiques from the judges (Simon could never remember her name).
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Alexis Grace (season 8, eleventh place)
Alexis' audition was soulful, but the judges didn't care for her girl-next-door looks. ''Just dirty yourself up,'' suggested judge Kara DioGuardi. ''Go home and make love to your fiancé.'' We have no idea if that second part happened, but Alexis did put some hot-pink stripes in her hair, and wore a formfitting onesie as she took Kara's advice to heart with a performance of ''Dirty Diana.'' Alas, a pitchy ''Jolene'' did her in the following week on Grand Ole Opry night.