Inspired by the controversy that arose after he admitted he had reviewed a movie only having watched its opening eight minutes, Roger Ebert has posted a very funny (and spot-on) listing of rules film critics everywhere should adhere to. For example:
Trailers. Have nothing to do with them. Gene Siskel hated them so much he would stand outside a theater until they were over. Trailers love to spoil all the best gags in a comedy, or hint at plot twists in a thriller.
I could not agree with this more. Fortunately, they don't show trailers at most critics' screenings, so I don't have to deal with them. But ever since watching the trailer for Cast Away, which showed you the entire movie from beginning to end (including Hanks being rescued from the island), I often find myself closing my eyes during long trailers. Watching a movie where you already know everything that's going to happen is boring.
Check out Ebert's complete list here.