You are totally right. You can't look at someone and know their status. It doesn't matter what ethnic group they belong to, only testing at the proper time will tell.
In my situation she was from South Korea, said was only here 5 days, however had a pierced belly, that is just so Cali thing with chicks here.... my reassurance :) Well what if she was with a black guy before me and he was African... I am in LA... no one knows these days.. especially with a prostitute right.