I have been there, probably 7 times, honestly and I did not notice a prostitution atmosphere, at least no the prostitution atmosphere that you can see in others countries in gulf or outside Qatar. Obviously I noticed this crazy couples, likes very nice Asian lady with very old and disgusted western man, is she a prostitute? Well, from my point of view she only has a very bad taste and he has a lot of money to waste around.
Personally I do not classify the ladies in this way and if is the case, well they should have a real good reason to do it.