Staying on this tangent... Pits have always come across to me as just big loyal lovable dummies with huge hearts and an intense need to please.
I doubt the animal is that much different. Just that people used and abused the "practically undying loyalty" aspect to train the empty headed muscle machines to be aggressive/defensive.
That is just how I view it. Nothing but personal experience with many members of the breed, and none professional.
Herp Derp