Bear in mind this does include street girls (although they are a minority and some of them are less likely to go for a check as well). Also, as Matrix has said, at least they're much more likely to get checked than civvies.
Receiving OWO is really rather safe (although there is a risk). RO isn't great (but not all STI's can live in the mouth/throat) and I really should stop that but I can't be arsed (because for some reason I still like it) and I'm still not going to catch anything life-threatening (unless I'm ridiculously unlucky and get something which is antibiotic-resistant or gets past the Hep B vaccine).
I've punted plenty (OWO and RO) and I've never caught anything.