By Lisa Schwarzbaum
August 19, 2009 at 05:44 PM EDT

This is my last link to That Movie About Oppressed Aliens, I promise–you may be wondering about now whether all of us at EW have been infected by alien ooze–but  I keep thinking about a friend’s response recently when I told him I thought he’d like District 9. “Really?” he said. “The trailer made it look pretty junky.” So I explained that the “junkiness” he saw was an essential part of the movie’s aesthetic and blah blah blah…But  the thing is, if all you had to go on when picking the movies you want to see are trailers running at the multiplex or on TV and YouTube, you’re bound to get a pretty screwy sense of how good–or bad–a movie actually is.

Sometimes, true, you can tell: The duller the romantic comedy, the more likely the trailer is to  tell you the whole story and use up the best scenes. But more often, preview clips rely so much on sensory saturation to convey elements of action, horror, suspense, or whatever, that it’s impossible for a thoughtful moviegoer to grasp the movie’s actual intelligence–or stupidity. I’ve already seen the trailer for Shutter Island two or three times, and I have no clue about the movie’s story or artistic style. I’m really looking forward to this one–it’s made by Martin Scorsese, it stars Leonardo DiCaprio, I’m there–but the trailer is no help to me. You?

I’ve come to accept that the more sophisticated and innovative a movie is, the worse the trailer is likely to be at conveying that sophistication: how can a 90-second spot possibly convey the exquisite build-up of psychological tension among a group of soldiers that drives The Hurt Locker? But I’ve also made peace with the fact that every once in a while, a trailer will come along that charms me silly. And I only have myself to blame when the movie turns out to be a dog. I’m talking about you, Beverly Hills Chihuahua. Got other examples?