So here they are, the worst movies EVER made:

Bug
The Descent
Vacancy

All three were supposed to be "ground breaking horror films" and all three were terrible. Bug... psychological thriller based around group hysteria... two characters, lame.
The Descent... horror flick about, I guess they were cave men? Something like that, I don't know, the movie was filmed so dark you couldn't really tell WHAT was happening...
Vacancy... what sort of horror film has 7 characters, two good guys, one dead guy four bad guys, and the surprise at the end? That 2 of the characters you've known the whole movie were the bad guys, plus 2 you haven't seen the ENTIRE movie, until the last 5 minutes. Just a horrible movie altogether.