Hey guys, I've got to chime in as well.
Unstable, human aggressive pit bulls are often the result of bad genetics, not
abuse at the hands of humans. This breed is supposed to be loving and trustworthy of humans to a fault, despite any abuse they might experience.
The "mean" dogs we hear about are nearly always the products of bad breeding combined with a bad upbringing.
You can't make a temperamentally sound, bomb-proof pit bull into a bad dog that will harm a human being, any more than you can make a genetically unstable, human aggressive pit bull into a dog that will be 100% sound and bomb-proof in all situations.
The dogs that we see spring back resiliently from abusive situations speak to good genetics triumphing over a bad environment. With such a large population of pit bulls, we are naturally going to hear of some who have bad temperaments. Many irresponsible people breed the "mean" pit bulls because they want guard dogs, and that indiscriminant, irresponsible breeding is what has gotten us into the trouble we're in today. Regardless of how the animal was raised, an American Pit Bull Terrier that attacks a human being is unacceptable.
Animal aggression is also genetic, and is a trait that is normal in the APBT. It can't be trained or socialized out. Training can help an APBT to control itself under supervision, but the animal aggression will still be there. An APBT that is animal aggressive is not mean or unstable--it's just a normal pit bull. It is very important to note that human aggression and animal aggression are not interchangeable, and a stable, sound APBT can differentiate between an animal and a human.
BTW, welcome to the board, Emylee!