During a recent movie visit, I was talking to a gentleman who was standing outside of a movie theater. He didn't want to sit inside while the trailers were showing. "I rather not see [trailers]. They're only big spoilers," he said. It took me only a second to realize how right he was.
Movie studios not only release multiple trailers, but they also release several clips and special featurettes prior to a film's release. Short 30 second clips often don't reveal much, but some are up to 4 min in length.
If you're an avid fan of a film, the special clips will entice you, but by the time you've watched all of them you have possibly viewed the best parts of the film. We even see behind the scenes and B-roll footage which use to be saved for the DVD release.
I'm an X-Men fan and will see X-Men: Days of Future Past when it is released. Fox has already released a 1:12 clip of the opening battle, but I refuse to watch any of the clips because I don't want to go to the theater and feel like I payed to watch a rerun. I made that mistake with X-Men: First Class. Not making that mistake again.