Why do I consistently read that Pit-Bull/Chihuahua breeding will result in tough puppies with bad attitudes?

I've been a Pit Bull owner for years, and have yet to own one that is even the slightest bit aggressive. It's the way you raise a dog that determines his disposition, in most cases. Of course there are situations of inbreeding and such that may cause temperament issues, but Pit-Bulls are NOT naturally aggressive dogs! They are MADE that way by ignorant, irresponsible owners. In fact, according to the American Temperament Test Society, Pit Bulls achieved a passing rate of 83.9%, while Golden Retrievers achieved a score of 83.2% and Beagles only 78.2%. That said, I Also own 2 Chihuahuas who are NOT snappy and who do NOT bark. They are two of the most calm, loving creatures I've ever met!! Biggest thing to worry about when visiting MY house of 2 Pit Bulls and 2 Chihuahuas is being licked to death!! The stereotypes are killing me and I for one am sick and tired of trying to defend these great dogs!