I find this sort of commentary interesting:

A confident, happy breed.

The pit bull's work has always been control and mastery of other animals - not humans. A correct pit bull is more often than not submissive toward all humans, and adores children. A pit bull that snarls, lunges or growls at a non-threatening human is NOT typical of the breed, and to keep such a dog alive endangers people, pets and the image of the breed we love. Nothing could be more incorrect than for these people-loving dogs to be considered a vicious breed. A correct pit bull is NOT a good choice as a guard dog - only an unstable pit bull will react with aggression towards a non threatening stranger. A normal pit bull looks upon all people as friends unless their actions prove otherwise. This happy-go-lucky attitude is a result of their confidence.

From a breeder site:

http://www.workingpitbull.com/aboutpits.htm