I've come across one "predatory" black bear in CA. At least, he was clearly stalking a backpacker ahead of me on the trail. No attack, though; he scurried off when we all started yelling and shouting. Heard later that the same bear had figured out that if you scared a backpacker, they dropped their packs, which had a bunch of neat food.
I thought of heading up there with a bear tag in the Fall, and just leaving a couple of backpacks on the ground.... I don't think it's baiting if there's no food, is it?
Back on topic, I have been witness or near witness to several black bear attacks, either mothers defending cubs or bears protecting food. Most didn't end up with direct contact/injury, but that was more luck than skill.