A couple of weeks ago a woman with a pit bull mix crossed the street to walk her dog down the side walk toward my wife and I. As the dog got close, its ears and tail dropped and back hair went up. I wondered why this woman felt compelled to bring her hostile dog so close to us. 

This was clearly aggressive behavior on behalf of the owner as well as the dog. She pulled her dog away when I turned to the side and pointed my household sized Mace can toward the dog.

This is part of the aggressive dog syndrome... aggressive owners.