+1
I'd like to state my answer in two parts, please:
The Ones That Truly Disappointed
The Hulk - I really didn't think this one could fail. But it did.
Underworld - There was once a naive girl who walked into a theater and bought a ticket for a werewolf/vampire movie, thinking that movie would do something very cool with a seemingly surefire concept. You guys... I was that girl.
Down With Love - So many people told me it was great--and it had Ewan MacGregor! I should have remembered that it's important, with an homage film, to know a little bit about what it's paying homage to. And, frankly, I could give a rat's a*s about Doris Day, Rock Hudson or the '60s sex comedy. Insert shrugging Smilie here.
The Ones I Knew Would Be Crap But Secretly, Deep In My Soul, Hoped Would Turn Out To Be Better Than I Thought... Only To Find Out That My Original Suspicions Were Correct
King Arthur - God almighty. They marched, they fought, and then marched again. And then some of them died. And Kiera Knightley wore a breast band. Huzzah...?
League of Extraordinary Gentlemen - This just didn't even come close to being anything worthy of its source material.
Dreamcatcher - I don't walk out on movies, ever, but I was tempted with this one. Seriously. I was embarrassed that I dragged my friends to see it with me.
The Butterfly Effect - Two words: Ashton. Kutcher.
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You were a demon and a lawyer? Wow. Insert joke here."