Well, as a veterinarian in private practice, I get to see all kinds of dogs. Most all of them are pretty good. There are good dogs and bad dogs. Dogs that bite are bad. We hear on a daily basis, "oh be careful, he was abused". That just means a muzzle comes out and extra costs for additional restraint. There must be millions of "abused dogs" out there. Sure, some have been but not near the numbers that we hear. Its usually a handy excuse for a crappy dog. Dogs are all individuals, subject to the same genetic, environmental and situational influences as the rest of us mammals. The American Veterinary Medical Association publishes lists of the top ten dogs most likely to injure a vet every year and I wasn't too surprised to see the weaner dog at number one if for no reason other than their popularity these days. Same reason a poodle or any other breed of great popularity could show up on the top ten list. Never feared getting killed by one though. Often the top ten will include, Rotts, Pits, Charpeis, Chows, Shepherds, Akitas, Malemutes, Dobies, St. Bernard etc. All of these generally get my adrenalin up when I have to see them, list or no list. Just plain meanest dog I've ever seen was a big yellow lab. Tried to kill me every time I saw him but knowing in advance and having a strong owner that told me up front that the dog thought I was lunch let me have the owner muzzle him and get some chemical restraint on board. The AVMA also published a study that showed 80% of people killed in the U.S. by dogs over a twenty year span were killed by two breeds. You guessed it. Pits and Rotts. Appears to be a genetic link involving both the breeds and probably to some extent their owners and breed popularity as well as situational opportunity and packing behavior, esp. with pits. Dogs that have most often tried to hurt me; #1 St. Bernard, #2 Rotties, #3 Akitas, #4 German Shepherds, #5 Malemutes, or something like that. Number one cause of death for St. Bernard is euthanasia for being vicious, ahead of cancer. Mean dogs just make for a long, stressful day.