That horrible movie that parodied "Meet the parents".
Actually, all those horrendous, disgusting poo-and-boobs-jokes "parody" films (Scary Movie, epic Movie, whatever. Just need to watch the trailer to known it's dirt poor)
All those hur-dur-retarded comedies are awful anyways. You know when the thing revolves around fart jokes, boobss jokes, scatologic jokes, fat people jokes and midget jokes, it's gonna be awful.
Also, a big part of the Superhero movie genre. Catwoman, Elektra, etc...
Bad fantasy-style-bandwagon movies like Eragon or Dungeon and Dragons (gee the dwarf was taller than almost everyone else and the hero was a friggen thief yet he was all sword fighting and waving magical wands and whatnot and ungh I'll stop here).
I'm sure I've seen worse things but it's those that come to my mind.