Could you please give specifics or facts about pits that pass agression tests and then kill someone the next day.
It doesn't happen. They were trained to fight other dogs and bulls and they were the only breed that could be pulled off another dog while in a fight and obey their owner and not bite them. Here is a link to the history of pits and how they have a low bite threshold for humans. The wrong kind of people own these dogs and it is ultimately hurting the breed.
http://dogs.about.com/cs/breedprofiles/a/pitbull_history.htm
A quality that was never bred into them was human aggression. Human “aggressive” (aggression may not be the most appropriate term, it is more likely that these dogs simply had a lower bite threshold) dogs were undesirable as these dogs required extensive handling prior and during their fights -
most of theses dogs were also family pets so no human “aggression” was ever tolerated.