A lot actually. Unfortunately, owners are not smart enough to distinguish pitbulls that have aggressive vs ones that do not. So they generalize to be on the safe side. Letting other people know that your dog is not aggressive should be depended on as an absolute as I have personally seen people say that their dogs are not aggressive but clearly show aggressive tendencies. It will also depend on the pitbull and how they act of course. Its not a one size fit all answer.