There is always a risk, you can only minimize it but not eliminate it. We have seen married couples swapping and not using condoms because they think that if the partners are not using condoms then both are safe. It is believed that most lifestyle people do not do high risk sex with sex workers or complete strangers in the street and take self-precaution not to get STD. I have been asked about unprotected penetration since my guest is married with wife, but no means no. I do not allow unprotected penetration. I take the risk in oral, as there is very little risk of infection. I like to receive oral, and what kind of contraption can work as a protective of someone performing oral on a vagina? If there is no protection while doing oral on a vagina, it is a bit too much to suck a condom and be protected, while the other is not protected. I am more afraid of herpes than aids while doing oral.