I think there are generic words like "dirty slut" and then their are pointed, specific words. To point out a scar or say something about nationality or race is too specific and I won't tolerate that. I also once had a muslim guy call me a "dirty fucking pig." Somehow, that just crossed the line. Perhaps because I assume that "pig" is especially nasty for a muslim. I told him to cut that right out and he did. If someone said anything derogatory about my nationality I would pull them up on it. Of course, I will often introduce my nationality, myself. To say, "Yeah! Fill my dirty Danish arse!" is one thing. But to say, "You slutty little Scandanavian skank" would just feel "off."