My friend Mark made me think of this...all the food that comes out at Thanksgiving that simply should not exist. I think this is mostly because he's British and his wife is American, so he can view our American tradition with a little bit of objectivity (though the fact that beans on toast exists---and he likes it--- keeps me from endorsing him as a connoisseur). It's purely a matter of taste, of course. My family loves red cabbage cooked in port and creamed onions....yours might not (probably especially not if you have kids).
What I think you end up with is a list of "must haves" and "never agains". And just to make this relevant to my blog topic, I'll speculate that some of these dishes have had the benefit of great marketing. Anyway, share your best and worst...I'll start:
Must have: cooked red cabbage, green bean casserole (I know, horribly unsophisticated, but I don't care)
Never again: sweet potatoes with marshmallows on top (blech!)