I, too, had a racist dog. He didn’t like black people. He grew up in small town Canada where there was only one black family and the dad was the garbage man, so I think he developed a grudge against him coming up to the house once a week, doing his business with the cans, and then leaving.
Eventually we moved to a more populated and diverse area and that grudge carried on targeted at any black men :(. I swear he was a good dog otherwise though lol