I do believe that there are some dogs that are just born with mental problems that make them a bit "off" & a huge liablity. We would be killing ourselves if we believed in the statement "there are no bad dogs" for it's just not true. However, some problems can be created by man, however, I personally own a deaf "pit bull" that was found on a 20lb chain when she only weighed 14 lbs & she was sick (hooks, rounds, coccidia, & Parvo) yet she has turned out to be the epitome of the "pit bull" in temperament. I won't accept any less. A good tempered, stable dog can make it through many situations without turning into a nutcase or an all-out aggressive animal.