The only two dogs that have ever bitten me were Chihuahua and a docile mutt I had played with all day long. (The Chihuahua bit me just because. The mutt bit me when I went to pet it 'goodbye' and it was eating.) I pet any dog, any breed, anytime I see one. (I'm annoying like that.)
If you ask a dog behaviorist, probably every bite can be attributed to some trigger of the dog's natural instinct. If we want to own pitt bulls or any other dog, we need to figure out how to protect others from the possibility of a trigger.
I will admit, my rottweiller that I had when I had a daycare for 5 years, slept with the kids at naptime. He was extremely protective and I never had an ounce of trouble from him with any of the kids. Even this sweetheart bit the UPS man though. The trigger was, the UPS man always brought boxes to my house, but on this one occassion, asked to use the phone. I stepped back to let him step in the house. The dog sensed a threat to me and bit him.
You just never know.