Here is my list (not in order):
Hour of the Knife: Railroaded plot with a twist to guarantee the ire of every player at the table.
Needle: Silly talking spiders that say, "Gee Whiz!" over. and over. and over. Actually, this silliness and politically correct "young gamer/child friendly" phase of 2E was one of the things that made me stop playing for a while. Any of them could make this list.
The Silver Key: The PC's can stay trapped in other bodies forever, and likely will.
Lost Island of Castanamir: bad gimmicks
Secret of Bone Hill: I know someone else praised this one, but my players were bored and confused. We scrapped it quickly.
Dragonlance: based on novels. "Come on ride the train..." We actually played the first nine adventures.
Gargoyles: see Needle
Puppets: see Needle
Howl from the North/Five Shall Be One: I bought these with great expectations of an epic quest, but discovered it was only a plot to destroy my favorite campaign setting!
Curse of Xanathon: see Needle
Now on the other hand, here are some that we played and enjoyed: Expedition to the Barrier Peaks, Tomb of Horrors, Castle Greyhawk, Beyond the Magic Mirror and Dungeonland, Ravenloft, Egg of the Phoenix, Ghost Tower of Inverness.
One final question: If we subtract the nostalgia factor, would Keep on the Borderlands make this list?
DM