Much of my pet peeves are more or less the same as Ms. Mason's. I'm tired of coming across grammatical errors. It annoys me a LOT when they are plentiful and I don't really look for them either. Some just leap off the page. Another thing that is starting to bother me is the way books are packaged or bound these days.
Pages feel like they have to be pried apart.
I know it's difficult to put out a perfect product but at least try to come close. With the price of books going up, customers demand more for their buck. I know I do. Dear TRR, I agree absolutely about the little things counting for a lot. One of my major pet peeves is typographical errors.