What do you think of book trailers as a marketing tool?

I am a big reader of all genres and I think that book trailers are silly. The "movie" and characters in my head when I read a good book are always going to be better than whoever is chosen to represent the character(s) on a commercial/trailer. I think the best marketing tools for authors are book signings/author meetings. Cover art is also a big attention-grabber. If the cover art is not interesting, then I don't pick it up to read the synopsis. My personal opinion is to forgo the trailers in favor of something less expensive....a good website can be set up to promote the book for very little or even free.