These threads usually get locked, however this one keeps going fairly peacefully so I'll add my .02 here.
I agree with PC on the media hysterics regarding Pits and biting. Many times though the breed is wrong and its not even a Pitty that does the attack.
That being said, however, I would like to address the saying "No bad dogs, just bad owners". Sorry but that saying is very wrong. There might not be a bad BREED as a whole but there are plenty of bad, bad, bad dogs out there. Poor temperamented animals, and I am not talking about an abused dog. I am talking about a dog that has severe temperament flaws, its a genetic thing in many cases and cannot be corrected.
And to people who say every dog that bites or acts fearful is abused. That is most cases is not the truth either. Most of the time its a temperament flaw in the dogs brain. I have only seen a couple cases of dog abuse that made the dog bite. And I have been a dog trainer and dealt with aggression for a long long time.
I have seen very nice Pit Bulls and Am Staffs. And i have seen some that seemed nice until pushed into an uncomfortable situation and snap and react quickly and dangerously. Same goes with GSD, Rotties, every single other breed of dog. They can all be dangerous, they can all have hidden temperament problems.
The real issue lies with the owners getting dogs and being ignorant the basics of dog care/training. Not knowing their dog enough to know what the dog will do if in a situation where it could be reactive. People constantly choose the wrong dog and then make excuse after excuse on why the dog is not working out for them. People need to start taking more responsibility for their dogs. Until that happens we'll continue to have these issues with breed bias and bite statistics going up and up and up.
ETA: also Pit breeds and the like do not have locking jaws. They do have very powerful jaws and they have the genetic instict (bred in to them purposely) to hold on to what they bite. Locking jaw is a myth.