Stupid previews

I am now faced with a problem, or maybe just a dilema. The movie Sky Captain and the World of Tomorrow is just opening. To me, this movie looks stupid. But unfortuatly, my not watching it may involve me missing a good movie. But is it worth the risk of watching movie. I bring an example, Hellboy. I thought it looked stupid, but some of my friends were going to it, so i thought id tag along cuz it had the potential to be good maybe. Well, it sucked. Another example, white chicks, looked either funny or a lame movie, i figured i wouldnt watch it and i havnt yet, but some of my friends said it was really good so i might end up watching it, im not sure. So why are previews so confusing, some movies look good and arnt, while others look crappy and often are, but may be good. Ya, Why cant all movies be good, that would be better.
-Ian
PS the Linsey Lohan SNL Harry Potter Skit is hilarious.