My dh came home with a staffy once - he was driving the boys to the village and found this poor dog by the road - he had no collar on and was injured - we think he was hit by a car.
Despite being in pain, lost and scared, and being picked up by a stranger, put in a strange car, and brought into a strange house, this dog behaved impeccably, even when he was being lifted/carried which must have been sore for him. Not even the slightest hint of a growl,or snap.
We handed him over to the SPCA, so he could get checked out by a vet (it was the weekend and our emergency vet charged £140 minimum on a Sunday), and let the police know about the dog. When his owners also contacted the police (he had been spooked by fireworks, slipped his collar and run away - they had been searching all night, and finally rang the police to report him missing), they were reunited with the dog.
We had already decided that, if no-one claimed the dog, we would offer to rehire him - he was that much of a sweetheart.