It’s good to have so many experts here in one place. As a layman... What do I look for to tell the difference? How do I know the difference between the pit that will play nice with my kids, and the pit that will play for a while and then suddenly rip their throats out? What do you look for?
GOOD reputable breeders who diligently socialize their puppies using the Rule of 7.
http://www.echowyn.com/Ruleof7.html
Backyard breeders and thugs will not waste that much time on their litters.
Indeed. Crowd sourcing is a thing of beauty and IMO FR is a fountain of knowledge.
For starters you can stop believing the horror stories you see disseminated in the media are the rule. There are dogs selected and bred for their aggressiveness by the criminal class. Historically any "Pit" that showed any aggression toward humans were undesirable and removed from the pool. Unfortunately general nastiness is prized by a certain demo, and you know who they are. It is a mistake to think magically removing a breed you personally abhor will also take away your fear. They will simply move on to the next breed. Akita, Chow, Sharpei, "Rockweiler", GSD...the list is long. Don't otherwise fool yourself. And of course, these are terriers, who by nature are dominant, and PBs are also powerful.
And I've said it before and I will again, they are not appropriate for many people. They need a knowledgeable and firm hand. Socializing from an early age is critical. The underclass denies their dogs this from the moment they capture them, and are typically abused to promote aggressiveness. Their progeny gets out there, sometimes into unsuspecting and unprepared hands.
I hope that answers your question. I've dealt with the obsessive PB haters here long enough to know better, though. I doubt you are so naive as to think you shouldn't supervise your children when encountering any powerful animal regardless of any preconceived notions about a particular breed.