I Was talking to one SP recently who says no Blacks and on asking her why she said they take liberties like wanting to pull the condom off etc. I said so are the all like that she said most are I was going to ask if they make her uncomfortable with endowmwnt size but decicded not to..
The skin color is more of a differentiating factor in this case rather than the underlying issue.
I attended an orgy in my previous life with complete strangers. It was just an itch I wanted scratched. There were men of all size, shape and race. There was one black guy. What I vividly remember is that all the SPs refused to entertain this gentleman. He was furious and got into an animated discussion with the pimp. Magically, one of the SPs, who is a well known British porn star agreed to entertain him, of course on the insistence of the pimp. He spent almost like 20 minutes drilling her and at the end of that ordeal, she fell on the floor and said out loud- "I am fucked". This experience remained in my memory as distinct.
Another SP mentioned that she avoided Indians as they usually tend to agree on the listed price but negotiate when face to face, and that they will ask for discounts for further meets. Found it amusing.
I think it all comes down to one's experiences, irrespective of the race. But the race then becomes the identifier.
Complex subject, I know. More difficult to resolve.