I usually read reviews or watch trailers and do other research before watching a movie so if it's a known bad film I'll usually skip it. That said I've obviously seen some crap movies in my time, but I can't count amongst those the four of your examples. I've seen them all didn't mind them and actually enjoyed JP2 a lot. They may have betrayed expectations but they weren't bad in a sense of Worst Film of All Time, I think. Far from it. Where then does Scary Movie 27 rank?