I grew up with Black Labs. I don’t remember them ever getting hostile with anyone. Visitors got the benefit of the doubt.
They can sense problem people. They protect their families. We had one as a neighborhood dog, taken care of by an older woman. He watched out for all the kids in the neighborhood.
My black lab will bark but that’s all he will do. He LOOOOOVES people and goes up to everybody to beg for pets and belly rubs.
That one looked like a lab mix. His ears were not as droopy as lab’s ears are and his muzzle looked a little thinner than a purebreed lab.
My old next door neighbor had a damn mean black lab.
The damn thing cornered me in my own garage.
I hit it in the head with a shovel, full swing.
They gave the dog away.
That is my experience as well. A couple I know went out to eat. When they got home they noticed that the dog's food bowl was half full when it should be empty. They checked their house and they had been burglarized. The crooks fed the black lab. Needless to say, that incident became a constant joke: "If I feed your dog a steak, will it show me where the guns are hidden?"