Does anyone know any books that tell you how to spot tactics?

I've been doing huge amount of tactic puzzles lately and I've seen a somewhat improvement in my tactical play. However, I want to find some books that can tell me what to look for in a position to see whether a tactic exists or anything that can help me spot a tactic. Any suggestions?

Tactics Trainer 15 minutes daily! For a year.

Try Ward Farnsworth's Predator at the Chessboard.

there are tactics to be found in every position ,the two suggestions above , are good .... one of my carry around books is .. THE COMPLETE BOOK OF CHESS STRATEGY.. by jeremy silman. points out tactical themes,,, and mating patterns . that being said you have to play , look , practice, repeat.

Check out the reviews for "Understanding Chess Tactics" by Martin Weteschnik.  I suspect it would be exactly what you need.

I believe there's a book custom written just for this:

Tal's Winning Chess Combinations - Mikhael Tal and Viktor Khenkin.

ISBN 0-671-24262-8

He shows you a pattern, followed by lots of examples of attaining that pattern using real game examples.

Sadly, I think it's out of print, and not available in algebraic notation. But a few years ago I managed to find a used copy on the net, to replace my original which has fallen to pieces.

[edit] I see it's still available at over 60 EU, bit steep for a used book....

NM Heisman's article on the "seeds of tactical destruction" contains  a good checklist.

http://www.chesscafe.com/text/heisman05.pdf