Some girls won't see overweight people are they "fattist", some won't see older people, are they "ageist", some won't see etc., etc..
To answer your question some groups whether we like it or not have been universally recognised as being victims of discrimination and titles given to identify these groups.
FAT, AGE, RACE etc are all recognised groups so any negative actions based on any of the items you mention would be legal grounds for discrimination.
Working girls choose to sell their body as part of their chosen "profession" but then feel its appropriate to say its my personal choice.
You can have a personal choice with regard to services.
eg We sell fish N chips not pizzas but personal choice as to whom you sell your chosen service to is discrimination and if its based on race its racial discrimination.
Ive given a few examples so here another.
Nick Griffin the head of the BNP
decides to make a public statement that Blacks, Asians, Jews etc are NOT allowed in his house.
Its his house so his choice, police walk by and say "no problem here".
One day poor old Nick decides he could do with the cash so decides to rent out rooms in his private house and places an ad in local paper.
Now we have a problem,....its still his private house but its now operating as a business so he can no longer say Blacks, Asians, Jews are NOT welcome in his private house.The police cant walk by and say Its his house so his choice. There is
a problem here
Only members of UKP can say that three's no problem here and many of them have.
Im sure some of them have a closer relationship with Nick than they care to mention.
I don't think some girls would have a problem with seeing black or asian people, its more to do with culture and how different cultures around the world treat women.
My understanding is culture is the ideas, customs, and social behaviour of particular people within a society.
A black guy with grandparents born in England, never visited the West Indies in his life is hard to assume he has West Indian Culture.
He has british culture.This also assume all black cultures as being the same and there is such a thing as black culture to start with.
Im sure you would accept difference in cultures from caucasian groups such Germans having different culture from English and sub divide that to all white English dont have the same culture.