When you pick up an attractive looking paperback in the bookshop only to turn it over and find, instead of a blurb, a list of quotes from various wanky publications. Somewhere within these quotes is some vague hint at what the book might be about but I can't be arsed to find it if the publisher can't be arsed to write a blurb.
I have no problem with quotes. They are very welcome endorsements, especially if they come from people whose taste I respect, but they are no substitute for a neat little summary of the books contents.
It happens quite a bit. I think it is shocking. There are enough barriers between readers and good books as it is without getting all enigmatic and highbrow. Tell me what the book is about, not what other people think about it, and then I might want to buy it. Dont, and I won't.