I think there's a bit of a disconnect here between "race" and "culture." One's ethnic or racial background is never an issue for me; I don't care so much about your ancestors as I do about you, and as long as you treat me with respect, that's all I really care about. I would be quite the hypocrite if I chose to judge people on the basis of physical attributes, given that I don't appreciate people doing the same with me. However, negotiating and haggling over price is an accepted cultural norm in some parts of the world, and tends to be less common in North America; this is the intervening variable that sometimes impacts my likelihood to see someone.
I don't care if you're white, brown, black or purple, I'll see you as long as you fulfill my detailed (some would say strict) booking requirements. That includes looking over my website, and taking note of the "Donation" section where it clearly says, in bolded capital letters, that
DONATIONS ARE NON-NEGOTIABLE. Since I do everything by email, I often receive the person's first and last name in their initial contact, and I can't help but notice that my "Hagglers" label (which I attach to every email where someone asks for a discount) is disproportionately filled with names from certain parts of the world. So, statistically speaking, I probably see a smaller percentage of certain ethnicities (relative to the number of inquiries I receive) than others, due to a higher-than-average propensity among people of certain cultural backgrounds to request lower rates.
Please don't think I'm being racist, I'm just being mildly observant. I should also point out that my "Hagglers" label also has a disproportionately-large number of young men attending university (who always ask for a "student discount" while forgetting I'm a "student" too) as well as a surprisingly-high number of young white guys who ask for discounts, while including pictures of their cock in their initial email (I have a separate label for these emails too). So, if you want to accuse me of anti-hagglerism, anti-studentism or anti-cockpicism, please feel free - I'll wear those labels proudly all day long.