When you have to lock up your dogs while having visitors, there is something wrong.
Reminds me of the time, living in the Bronx, when my Aunts bff, who lived across the hall, her oldest grandchild was living with her and had a German Shepard named Rocky.
Rocky was out for blood. Apparently there was no training this dog. It was actually smart enough to unlock the front door, get out and attack the mailman. Rocky took about 1/2 of his calf.
After that, they had to padlock the front door, as well as the bathroom door (padlock, with lock and key). The bathroom door was padlocked so we could go and visit Mary.
I don't think it's the breed of the dog, but what it is trained or NOT trained to do. We also had a German Shepard. Anyone could come and go into our apartment without being attacked.
The only time Dukey attacked was 1 - when a bullish girl decided to try and attack my sister while she and my Aunt were out walking Dukey. He didn't get her. 2- While my Aunt was bringing back Dukey from his walk, a stranger was apparently following her and stuck his foot into the door so she could not close it. Dukey went on the attack and the perp ran away.
One other time, with my fab Duke....there was a German Shepard that lived all the way up the block from where my Aunt & Uncle lived (when we lived in the Bronx, we would go spend the summer in the "country"). Duke was getting old, so we decided to have him live in Long Island.
This German Shepard from up the block, got loose and came onto our property. We were all little kids and were absolutely frightened. Dukey took this dog and literally threw him into my Aunt & Uncles metal screen door.
This dog ran away and we were saved.
Had a friend that had a large white shepard. You were OK when you went in the house, the dog sniffed and left you alone....one night they came home and found the side door open, the kitchen and living room had blood and blood trails, the dog was quitely sleeping in his bed...did his job and went to sleep. Nothing was missing from the house, just some blood from the crooks was missed
Sometimes docile dogs are separated from visitors who have an irrational fear of all dogs. And some do.