For me it was "The Sound and the Fury." I can sort-of, kind-of see the genious it took to write that type of novel, if I squint really hard. But that book turned me off Faulkner for good.
My English teacher conveniently omitted the fact of Benjy's autism, and I spent the entire first section almost cross-eyed from frustration. I kept thinking, "This guy is supposed to be one of the best authors of our time! HOW!!!?!?!"
I think I've told this story on these boards before, but my refusal/inability to read
The Sound and the Fury all the way through is why I ended up with a PhD instead of an MA.
It took me many years to develop the ability to walk away from a book I couldn't stand. It's been very freeing. One of the books I didn't make myself finish was by the guy who wrote
Wicked, I think: a ghost story, and usually I love ghost stories. This turned out to be a depressing, disorienting, unnecessarily protracted voage with a main character I quickly came to loath. Started skimming and discovered that I hated even more where he took the story. Ugh.
The Nanny Diaries just horrified and depressed me. I know it was fictionalized, but I'm also sure there are indeed couples out there who have neglected accessory-baby children and conceive more of them to keep their marriages together, and the thought of all these poor kids just sucked all the humor out of the story for me. That, and the fact that the protagonist put up with such abominable and dehumanizing treatment. I kept reading in hopes that the nasty boss-lady would get her comeuppance, but the story ended with her having the upper hand of pretty much everyone. Gads.
Similarly,
The Devil Wears Prada--I couldn't see the humor in the protagonist letting herself be treated that badly.
Anne Rice's
The Mummy read like it was something she wrote when she was fifteen years old and then, decades later, when her publisher wanted more AR titles, she pulled it out of a drawer, dusted it off, and had it published.