I do this too, and my wife thinks I'm insane. But I'm not really trying to judge if the book is good or bad. I just want to know if it's good. And there are more good books with good first few pages than I'll be able to read in my lifetime, so I don't really lose a lot by accidentally not reading a good book with bad first pages. On the other hand, by accepting bad first pages I risk having to suffer a whole bad book!