I've been lucky in my fiction reading. I can't remember the last time I didn't finish a novel. I do have novels that I need to reread because I read them when I was young and arguably unable to enjoy them because of that. Samuel R. Delany's Dhalgren tops that list.

On the other hand, I remember actually throwing David Friedman's The Machinery of Freedom across the room when he suggested that slavery was an agreement between enslaver and enslaved. Jesus H. Christ ....