Bro think about it this way - any which way there is a chance of exchanging bodily fluids (saliva, blood, pus) then there is a chance of catching infection (bacterial or viral). This exchange is possible through cuts on skin/boils, mouth, ass, dick, and pussy. So if during b2b she has a skin cut (broken pimple/boil) or rubs her pussy juice on your dick (or on a cut on your body), you can get fucked depending on the exposure. So just give it a thought next time you go around fingering a whore's pussy with a paper cut on your finger that you dont even remember.
I really dont understand how men on this forum are super excited to lick a whore's pussy and claim proudly that it got her wet or get happy with DFK and claim it to be full GFE. It is a considered completely stupid to do in the first world countries. That pussy or mouth has been constantly eaten or fucked (for 365 days x years of working) by DIFFERENT MEN. Think about the odds and probability of catching something. Many times they dont even wash in between sessions or insist on CBJ. Heck sometimes they dont even care for a condi. And there is an 80% chance (as per my limited experience) that if a therapist blows you in MP then she is taking personal clients outside for full service.
You are literally playing russian roulette each time you dip your exposed tongue, finger, or dick in a whore's pussy or mouth that could give you a life altering disease.
Disclaimer: chances of catching something varies for diff. STDs/STIs depending on the circumstances/exposure. But one thing is certain - PROBABILITY IS HIGH IN CASE OF A WHORE. Simple maths hai.