Well from what I've seem, Pitt Bull's and Rotties are not naturally mean dogs.
People with bad attitudes get them because they think they'll make BAD ASS dogs. Then they TRAIN them to be that way.
My dog is 1/4 Rottie and 1/4 Pitt Bull and 1/2 Chesapeake Bay Retriever and is gentle as a lamb. He caught a mouse one time, and didn't even hurt THAT. He goes to work with me every day and little kids crawl all over him. They pull his ears, tail, poke him in the eye's, no matter. He's still a big softie!
But then I knew when I got him he was going to be BIG and as a responsible pet owner I made SURE he was trained properly!
So in my opinion if someone's dog attacks someone, it's the OWNER'S fault, NOT the dog!
Dog's as a rule are only what YOU make them.