The only film that I watch that I would consider a true guilty pleasure is "Barb Wire".
Most of the films listed in here are movies that people seem to feel strongly about one way or the other (I hate Willow for example, but consider Big Trouble in Little China and Top Secret to be some of the greatest movies ever made). These are all movies that are at least well made, with decent acting and a plot that doesn't make you cringe at the sheer stupidity of it all. I don't think that kind of movie can truly count as a guilty pleasure. A guilty pleasure has to be the kind of movie that you would hesistate to mention you enjoy, lest people think less of you.
Barb Wire however, is a film with essentially no redeeming features. It exploits blatantly Pam's body, the plot is a poorly conceived rewrite of Casablanca, none of the characters are interesting or especially well acted, it isn't even faithful to it's source material (a very old comic).
However, there's just something about the movie that endears it to me. Part of it is that Pamela Anderson just looks soooo good sneering while wearing skin tight black leather. Part of it is that as a friend pointed out to me, in many ways Barb Wire IS what Casablanca was supposed to be. A B-Movie made as a throw away. Casablanca just happened to wind up with great actors and a script that has struck an eternal chord in people. Barb Wire was .... not so lucky. Plus I like Pam, she's so disarmingly frank and simply just doesn't take herself too seriously.