I think anyone who's watched Mystery Sceince Theater 3000 knows too many bad movies. Some of the more memorable episodes are Manos: The Hands of Fate, The Deadly Mantis, The Final Sacrifice, Hobgoblins, Overdrawn at the Memory Bank, and The Wierd Creatures That Stopped Living and Became Mixed-Up Zombies.
Also, The Lighting Theif and A Series of Unfortunate Events are bad on a personal level in that they completely trashed the book/books they were based off of. Not to mention that both movies are based off of my favorite book titles.
Birdemic is also a stink bomb in its own way. as well as Santa Claus and the Ice Cream Bunny.