It gets better (or not)

Some readers may drop a book after the first couple chapters or first fifty pages believing the entire book will not improve if reading continues.  Others would rather see if the book improves once it reaches its climax and ending, and are willing to get to the end before judging.  What do you do?  How accurate are you if you predict a book will suck more if you continue or get even better if you continue?

I always read at least halfway, and I try to make it to the end of even bad books, but it's not always possible.

i try my hardest to finish them but sometimes im just not able to

like with a canticle for liebowitz, i powered through the second part (fiat lux i think) but couldnt make it very far into the thried mainly because after brother francis died there were no likeable characters

I finish most fiction books I read, although I have stopped due to lack of interest, especially in some more highly-regarded titles.

I stop frequently on non-fiction and informative books. If I lose interest in a subject, I quit the book cold turkey until the time comes where I'm interested in said subject again.

I'll be honest, I pretty much reader about the first chapter and I'm either in or I'm not. Fiction that is.

Even if I hate a book after the first few pages, I see it through because I'm a completist. Same goes for pretty much anything. If I'm really not liking it, I'll probably read something else, and eventually come back to it.

I tended to stick too long to books that I hated in the hope of them getting better. In the end, they almost never did and I did end up dropping them.
After recognizing this I now skip a bunch of chapters ahead (mostly to about 3 quarters in) and read a few pages to check - risking major spoiler is more acceptable than wasting hours on a shit book, to me.

If I'm checking out a new author I've never read before I'll usually try to take in the whole book. If it's an author I'm familiar with and yet another one of his/her books are sucking, I'll probably just drop it.
Unfortunately, the first time I read Ann Rice I forced myself to finish Interview With the Vampire. Shitty ass book. As far as vampire books go it was probably worse than Twilight.