We always had rescue Dobermans, and our vet said that he was always nervous around Pit Bulls. Said that they can be sweet and nice pets for 9 years maybe, then one day the bomb in their brains will go off and they will attack.
Around here the cops tell us if they pick one up, it'll be dead when it reaches the pound. Some years ago 2 pit bulls attacked a cop, but he was finally able to shoot them. While he was bleeding and trying to get to his car, the owner sneaked around and took the tags off the dogs. The cop remembered seeing tags on both of them. This was right before microchips.
That said, this weekend next door neighbors got a pit bull, a large female from someone, not a shelter. They have no idea of how to keep her in, she keeps pushing out the fence and joining me when I'm in front of my house. She is friendly and acts nice, but.....