I get a lot of "red zone" dogs in, and Jock tells me the dogs I should trust, and the ones to keep an eye on. So far, he hasn't steered me wrong. If he wont approach a dog, I'm wary. If he wants to be friends, then I'm happy to work with the dog.
We recently held a recall clinic, and Jock, obviously, was there for the 2 days. He's got an incredible recall, but he's also showing his paw at a few other things, like weaving off lead through the traffic cones.