I don't think I have a real answer for this. I know at least one person who likes every movie I like. So I will pick a movie that my friend ED and I watched alllllllll the time in college, but that was considered a total disaster by most critics, and was a stupendous commercial failure as well. I am, of course, talking about Ishtar (1987).
Ishtar is the far-fetched tale of a singing/song-writing duo who get accidentally embroiled in middle east intrigue. Think North by Northwest crossed with Some Like it Hot. The singers are played by Dustin Hoffman and Warren Beatty. Yeah.
I think that maybe people didn't realize that Ishtar is supposed to be funny. I'm not sure how they could have missed that fact, but perhaps the presence of Hoffman and Beatty threw them off? If it'd been, say, Steve Martin and Chevy Chase, then would people have understood? But it's Beatty and Hoffman being so very serious that makes Ishtar funny! They belt out insane lyrics like "Hot fudge love, cherry ripple kisses" with perfect earnestness, they struggle through the desert leading a blind camel, Warren Beatty's character idealizes Dustin Hoffman's character for being so much better with women... and they never crack a smile or wink at the camera. How anyone can help but laugh is beyond me.
ED and I used to quote this movie all the time, and sing songs from it. Our favorite bit of dialog we would do with each other came from the above scene and went like this:
WB: "I'm not crying. A piece of sand blew in my eye."
DH: "Wait a minute -- a piece of sand blew in your eye? I thought you said there was no wind in the desert."
WB: "Must be one of them once-in-a-lifetime occurrences."
Not exactly standard humor, I grant you. But it made us laugh and laugh! We'd do it whenever a sudden wind kicked up.
Our favorite song from the movie went like this:
Telling the truth can be dangerous business;
Honest and popular don't go hand-in-hand.
If you admit that you can play the accordion,
No one will hire you for a rock-n-roll band...
(I found the song on mp3 here if you want to hear it.)