The "Sociopath Next Door" (excellent book) makes a very good point - it is not clear that being a sociopath is a disorder or an illness in that it doesn't appear to have negative effects on the person with this behavior. Indeed it makes the point that there are many environments where having sociopathic behavior is a decided advantage.

What I found truly frightening in that book was the section pointing out the downfalls of the results of the Milgram experiment (most of us will do what we are told by an authority figure, even to the point of torturing/killing) with sociopathic behavior by a minority.