I've had a few busts on the book front
1) The polytunnel companion. It doesn't tell you anything that you can't find for free on any reputable polytunnel website.
2) Permaculture: a designer's manual by Bill mollison. I should point out that this book is not crap - just not much use in temperate climates and cost me a fortune.
I asked OH which gardening books he'd put on this list (he doesn't read most of my other ish stuff) and he said "most of them". While I don't necessarily agree, I know what he means - most British gardening books are talking about the south of England and mention leaving things a couple of weeks later further north.
None even touch on our specific situation up here - maybe I'll have to write one. Although it wouldn't sell many - not enough people
Can't think of any other's at the mo but they'll come to me.