Two come to mind:
Fifty Shades of Grey (the first one). It's awful. Boring, badly written, and the sex is dull. I only finished it so I could say I had and talk about it with a friend who had read it. It has given me leverage in conversations, though. Lots of people who want to talk about it haven't read it, so I get to win all those arguments.
Three by Ted Dekker. My wife gave me this book as a gift. Somehow, I have managed not to divorce her.
It is atrocious! It's a cheat and badly written. As Spinal Tap said, "It's a fine line between stupid and clever." This stays on the wrong side of it.