You could always, you know, educate yourself on the movies beforehand. That's not a jab... I kinda' know what you mean. I mean, I've gone to see movies before that felt somewhat different from the trailers, although in my experience this has rarely actually been a bad thing. Usually it was a movie I didn't want to see as much that other people did, and then in the end I ended up liking it more than I expected. The Sixth Sense was like that, as was Spirited Away. There are a couple others I can't think of right now. But yeah, at the same time, there have been a few times when it's been the other way, and I can state for a fact that I probably would have been disappointed by Crank too if there wasn't much action in it. If I ever saw that one, I'd have been expecting an action flick and would likely have been disappointed if I walked away without getting one.
I'll have to disagree with you on Pan's Labyrinth, however. Granted the trailer may have led you to believe there was more fantasy in it than there was, but that wasn't the point of the movie and I never thought it was because I knew well beforehand what I was getting into. And, generally speaking, I do this with all movies. I almost never go in without reading some opinions and such first. And I don't see why you wouldn't care about the other stuff happening in the movie. The fantasy stuff augments it, but it's good enough to stand on its own. And the fantasy scenes weren't lame, they were superb.
Still, I feel you on the main point. Honestly, I don't think trailers are a good way to convey anything about a movie, really. They just can't do it. A text synopsis is always the better option, which is why I generally don't bother with trailers other than to get a general visual sense of a movie, and instead just go read something about it on the internet somewhere.
