I think Heart of Darkness is one of those books that are a lot of work to go through, but when you finish it, you realize it was a pretty great book. Jude the Obscure was another book like that. I had to read it for my senior seminar (and then write this huge paper on it), and so I had to force myself to read it day after day. That book was SO GOOD.
Anyway. I have quite a few that I haven't finished, and have no intention of finishing.
Wicked (by Gregory Maguire) I got pretty far into this one. I'd still like to see the show, though.
Lucifer's Hammer (by Jerry Niven and Jerry Pournelle) I kept trying to read this one on a daily basis, and couldn't keep myself interested.
Obsidian Butterfly (by Laurell K. Hamilton) I think this one may have scarred me a little. ugh.
Bag of Bones (Stephen King) Also scarred me. Ghost sex, with skin peeling off. tmi, seriously.
The Historian (Elizabeth Kostora) boring and nonsensical
Their Eyes Were Watching God (Zora Neale Hurston) I really wanted to like this one, but I couldn't get past the dialogue. I have no tolerance for accents in books.
Shamela (Henry Fielding) Didn't like Pamela, didn't really appreciate the humor in Shamela.
several romantic fiction books by Janet Evanovich. I got them on CDs from the library because I was listening to fluffy books I didn't have to pay much attention to (new baby, makes it hard to read). I had a bunch of them on hold, and I was desperate, so I wanted to give them a fair try before sending them back. Wow, they were bad. Wow.
And my favorite book to dislike, The Dragon and the Unicorn (by A.A. Attanasio). Let me share it with you.