I have known Pit Bulls that would not harm a person (Unless you were trying to either harm them or one of their protectees) and pit bulls.. Well the one dog that ever managed to cause me pain (Did not exactly bite me, but tried) on purpose and had any measure of success at all was a Pit Bull.
I have been bitten by a dog once.. He did not mean to and it was clear from his actions he was sorry,, That was an albino shepard.
The Pit managed to strike a fingernail while trying to bite my wrist but I was too fast for him (Fairly good at reading animal body language so I knew to get outta the way, just not quite fast enough) he is the only animal ever to "Get a piece of me" on purpose.. Though even there he did not break skin.
So Yes, I am cautious around them.. But I've had other breeds try to bite me too,, Like the pit, they filed, unlike him they did not even get close.