I was at the vet once when someone came in with a little pit bull puppy that was very snarly at everyone but the owner. The vet came out (into the waiting room!) and gave them a lecture about getting their puppy around other people and training it better or they would need to put it down. I've never seen him so upset with a client in public. It seemed a bit unprofessional, but I think he was just very serious about getting the point across. I think it has a lot to do with training and teaching any dog that other people are okay.