Haha.. funny how peoples tastes can be so different.
Whenever I'm watching a REALLY bad movie, or hear a REALLY bad song, I can't help but think.. "Wow, this is somebody's _favorite_ song, how sad"
Yeah, taste accounts for a lot. There are many pictures that I think were absolutely wonderful, that a lot of people seem to think were horrible.
Dune
Blade Runner
Seven
As for bad films, I've been lucky enough to completely avoid most of them. So, the worst films I've NEVER seen:
Ghost Dad
Leonard Part 6
Glitter
Battlefield Earth
And the number one all time bad film (which I'm proud to say I own on Laserdisc):
COOL AS ICE

I've tried to watch it, but never made it through more than 15 minutes or so (I have a weak stomach).