how far do you get into a book before you know if you want to read it or not

I can usually tell by the first chapter at least,I try to read what the book is about before I read it and sometimes can tell by that as to if i will like it or not. Sometimes the book cover and the discription look good and I start reading it and I dont like it.

If I dont like a book and cant get into it by the time I am starting the 2nd or 3rd chapter I wont read it anymore. But one book I actually only read the first couple of pages and I jus put it down and havent picked it up since!

I have some authors whom I do not like to miss. Frederick Forsyth and Arthur C. Clarke and two of them. Recently I read Da Vinci Code and now am interested in Dan Brown and got the urge to read his other books. I know I wont be disappointed, because every one's opinion is that the books are good. So recommendation matters.

I will only read a few pages of it to see if it is interesting enough for me to spend my time to read the rest of it. I really don't like reading. I have a very hard time remembering what I just read and I have to read over it a few times before I will actually comprehend anything. I really don't have time to read. I have to have complete silence when I read something also and silence is hard to come by when it is time for me to sit down and read something. I only read things that I have to read and hardly ever read anything that does not help me with things in life.

Probably a chapter or 2. But if it is one in my favorite genre and I don't have any other book at hand, I would force a few more chapters so hopefully it becomes "likable" then. :P

before I bought that book, I will read the sinopsis behind the book. If the story is interesting for me, I will buy. so I seldom get bored with the story, and I can read it until finish. If I didn't interested with the story, I can finish it too, except there is a other important things. so I will stop reading and put into desk. then I will never read it again.. -__-a

I get bored easily, so if a book can't grab my attention by the first few pages I probably won't be reading it.