Isn't it a question of nature of nurture? If you really are attracted to women of other race or ethinic backgrounds, but holding back because of your nurture - well - you are missing out.. Otherwise, you're not.
Sexual attraction is sort of a primary response.. I don't think you can control it (inwardly, anyway). You shouldn't trry something just because you think society thinks you should. On the other hand, you shouldn't not try with a SP that is of different race/ethnicity because you are conditioned not to, even though you have an urge. What's the worst that can happen.. you blow, say £150 on a punt that's not right for you. In the scheme of things, that aint bad.
A good mate of mine is black and does not find black women remotely interesting.. he has married a white woman. Another good mate of mine who is white has married a black girl. It's horses for courses.. it isn't racial - its a sexual preference. To say someone is racist because they don't fancy a particualr race is crazy. However, given SPs are performing a business transaction and since they are being paid, it would be logical they should she a client of any race regardless of whether or not they attracted to that race. But, if that race is going to put them off, then they probably should state it because they are unlikely to provide a good service to them..
FWIW, I grew up in a largely monocultural white society (mainly European ancestry). I find olive and brown-skinned women a real turn on; white's OK, while orientals and blacks don't do much for me (yes, I have fucked them). It's a shame, as there is a tidy oriental civvie who is showing me a bit of interest. And, I have to say, I think there is nothing sexier than the pink pussy on black skin... But to call me racist for that is nuts, because although I would not give them equal opportunity to my dick (not that too many come asking), in all other respects they are, like everyone else... people.