The book is largely common sense, but apparently people need permission to exercise common sense these days (either that or it's so seldom used that people no longer recognize it for what it is.) Basically, don't hire people who are going to create negativity in the workplace. If you've already got them, get rid of them. Watch your own behavior to make sure you aren't one of those who should be gotten rid of.
Of course, common sense isn't always politically correct, so it's going to be a long time before this can be widely implemented.
I really loved this book. I thought it was pretty funny, and so true. I bought it obviously because I work with a**holes but I'm also a supervisor and don't want to be one myself. My own supervisor is one, and when I showed her what I was reading, just to see what she would do or say, she went right to the chapter on "Do You Want To Be An Effective A**hole?"