I had to put down James Joyce's Ulysses in book and audio form, I never had to do that and hopefully I won't have to again... the book was very painful to read.

That's actually an interesting point.
I don't necessarily think Nabokov's Lolita is a "bad" book, but the style of writing required me to really work at it. I eventually quit half way through. Then I checked out the unabridged book on CD from the library and really enjoyed it.

I completely forgot I dropped that book. I gave it good chance but it just lost me.

Gerold's Game by Stephen King. Boring as hell.

Some computer gone stalker book by Dean Koontz. To slow to start.

Left Behind. I just didn't like how the people were acting.

If a book isn't appealing to me it takes me forever to clog through even the first chapter. And since I don't overlap books, if I were to keep reading something that wasn't holding my attention, I'd essentially be keeping myself from reading something I might actually enjoy. I can usually tell within ten pages if a book or author is just "not my thing"... not even necessarily 'bad'.

This is what I do, pretty much. There have been a few that were very boring from the start, I put them down with the intention of going back to finish. I had one book by Robin Cook, who can usually write something at least entertainingly bad, it was literally falling apart I'd picked it up and put it down so many times before I finished. The ending was as dull and predictable as the beginning.

Sometimes staying with a book has its payoff though. I, too, research before I buy, but not everything can grab you right off the bat. I think it's good to finish what I start if it's not excrutiatingly bad. I just finished Cat's Cradle and I wasn't really into it, but if I'd dropped it I would have missed on such a great ending!

A friend once told me, "Life's too short to finish a bad book." I guess that can be true, but c'mon I'm not that much of a hurry, besides I need to calm my ADD not aggravate it by jumping from one book to the next.