I have to disagree. This is like saying that most people never consider sleeping with their neighbor's wife. Bullshit. I think people who claim that they never have such "bad thoughts" are lying - either to the world or to themselves. If you refuse to admit to yourself that you've considered it, you can never have an honest conversation with yourself and work out the rational reasons why you shouldn't do it. This is how "normal" people end up suddenly doing things totally seemingly out of character; they failed to be honest with themselves.