A few years back, a friend gave my partner and I a selection of 4 books like this from a website which packages them up with a few descriptive words (so you get some feeling of what you're buying and don't get the same thing twice).

They ranged from “not very good” to “fine”. I guess it depends on whether the bookshop is trying to get readers to try new things, or whether they're just trying to get rid of the stock they can't sell...