The difference is that the provider of the service is a 'business' and should not discriminate. If that provider needed the same service she provides (but had to go to someone else because she cannot do on herself) she TOO will be making choices because she is paying.
Not saying racism is 'ok' under certain circumstances but if, for example, I do not like to go to black ladies, they will never know cuz they just won't see me. Still not right of me to feel that way but no feelings get hurt.
I agree with smells. Many people cook foods with improper ventilation so clothes reek when they get on the bus.. Can't comment on skin because I have not been that close with a naked brown person or if it is even possible that that can happen (assume it is skin surface picking up from clothes, not inside out). Does not mean all people of that race live the same way. If your great grand parents were chinese, you will not suddenly become a white man but you will probably not eat the same stuff etc etc.
Having said all that, if I knew someone was racist, why would I want to see them? Would not want to support their business nor subject myself to their attitude.