Has anyone ever known of a maddog puppy?
Usually, mean and aggressive dogs are the product of human neglect or abuse.
Some breeds have developed a reputation for being naturally aggressive. Most German breeds, and others mentioned in this post. My first dog was a German Shepard, who I will never forget. One of the many memories was when I was 12. The day he put a neighbor kid, 4 years older, and 50+Lbs heavier up into the back of a pulp truck, as he threatened to kick the crap out of me. He kept him there for over an hour, until I called him off.
I'm sure everyone on this thread loves their dogs. But if I am confronted with three dogs running at me with intent in their eyes, I'm shooting first, and asking questions later.
On the other hand if panzer426's German Shepard runs up to me wagging his tail, I'd drop down on one knee, and greet him.
I would hope we all would know the difference.