I have a Labrador German Shepard mix. Smart, sweet and very protective. His only fault is that he is the biggest racist Ive ever known.
Interesting that you should mention that. We had a beautiful Collie years ago. She had a sweet, friendly disposition to everyone until....one day a "door-to-door" religious group arrived at our front gate. There was a black lady among them and the Collie reacted in a way that I've never seen before.
I don't think that it's racism on the dog's part. It is that they are seeing a human being that's very different from what they're accustomed to.