Well I don't know if the lady I had sex with in cancun Mexico was certified which I doubt but it was at a house they brought the lasts down and you got to pick does this sound like a CSW house or just a prostitution house they provided showers afterwards
It is said that most CSWs (certified sex workers) are not high risk for HIV because most places (especially in industrialized countries such as the US and Great Britain) that employ certified workers require monthly STD screenings in order for the worker to keep their position, and the vast majority of sex workers always employ condoms because they want to protect themselves from all of the clients. That being said, of course you would never ever want to engage in unprotected sex with any sex worker.