Generaly I like movies with a good twist, or that require a bit of thinking, so things like The Usual Suspects, Seven, Memento or Shutter Island (though not so much films that fall into this category but which I feel cheat, like The Prestige.

I also quite like 'clever protagonist outsmarts the antagonist(s)' films, like The Amateur, Law Abiding Citizen, or, I suppose The Usual Suspects also falls into this group as well, though I prefer it when the cleverness is plausible and not crazy accurate prediction on exactly how people will react to chnaging evens (Law Abiding Citizen has a bit too much of this).

But they're not really guilty pleasures. My guilty pleasures are American Hich School movies, like 10 Things I Hate About You, Heathers, or even Bring It On. Bonus points if it features an unconventional teacher or coach who turns underdog teams or academics around, like Coach Carter or Dangerous Minds.