I'm not saying it's a bad movie. I don't like bad movies.† I love that movie.
I just feel guilty about it, because it is sooo prevered and irreverent, and fetishistic. And violent for that matter.
I was raised surrounded by religious fundamentalists, so yeah, that guilt is a sexy whip I'll be carrying with me probably forever.

† if I don't like it, it's bad, by definition. far as I'm concerned, other people's opinions are either the same or wrong. :P
when push comes to shove everyone puts their own value judgements first, even if their first value might be a democratic one.
the interpretation of 'worst' is subjective, i chose the adverb definition in 'worst guilty pleasure'; bad movies are only worth mentioning in so far as to assign them damnatio memoriae.
if something is "so bad it's good" then it clearly isn't bad.

(sorry, i've been writing an unrelated argument somewhere, can't help my brain is in argumentative pedantic mode right now)

(i know 'guilty pleasure' often means good movies with problematic parts, but I would roll those into it being a less good movie not it being fun haram; my reaction then is disgust not guilt)