I've known two pit bulls in my lifetime, both of them obedience trained and both of them seemingly good and mild dogs, owned by good people who readily admitted that they are unpredictable.
One approached me and sat down next to me and gave me a look that I read as "I can tear you to pieces and I'd enjoy every minute of it"
Just as I was cautiously stepping away, her owner (my brother-in-law) warned me that she had an instinctive mean streak and that I needed to keep my distance as long as I was in her territory (his back yard).
The second one I encountered while visiting a friend in his home. It lunged at my son's face for no obvious reason and was stopped a fraction of an inch short of sinking her teeth into him by her owner who had her on a chain and later admitted that as good a dog as she was, she was truly unpredictable, which is why he kept her on a chain whenever he had company.
Not knocking the breed you love, because they are faithful pets to their owners, but if you don't own them, you have reason to be wary of them!
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You know childhood is over when a puddle seems like an obstacle instead of an opportunity.
Is Too! Is Not! Is Too! Is Not!