1st and foremost, what does ethnicity have to do with it?
K-Girl or any other provider has had many boys Tools down there.
If you want to make sure that is not the case, get an earlier session in the day, k-girl or not.
K-girls do not do BBFS, so, if you got a taste in your mouth it would be latex or lube if you are dining between CFS.
Hygiene is very important to K-Girls, most of the time they shower before and after every session, usually with you, which is nice but they clean themselves up every time. They are very clean, as I am sure other providers are.
As you can tell by my Moniker, I "love" Daty and if a provider enjoys it as well, homerun.
Not to flame on you but
If you cant tell if a girl, k-girl or not is enjoying your daty session, I think you may need to change your technique.
I find most girls I have been with Act at first, until they feel comfortable with me, its normal as I am new to them. Once they are comfortable, some of it may be acting, but, when she O's during Daty, its obvious.
I also do more then one session with ladies, as once they are comfortable with you, it gets much better.