I only perform oral sex on men I know well and will not swallow unless I know his sexual history, including current lovers. I don't sleep around. And I don't play with people who do. In my younger days, I was less cautious but these days, I'm extremely cautious and not willing to risk my health nor the health of anyone I love for a fuck.
Men and women are now coming down with throat and mouth cancer due to HPV. It used to be mostly identified with cervical cancer in women but since oral sex is now common among the population, the virus is being transferred to the mouth and throat. Chlamydia is also being found in the throat more often. So it isn't only HIV and herpes you have to watch out for these days.
Sex is not worth dying for so only play with lovers who have a limited number of partners and who do not take risks with his or her health. Blowjobs with condoms, pardon the expression, suck. It feels strange both for the giver and the receiver. It's better to trust your partner implicitly and know that it is safe to play with them.
I have three lovers. One who has been with me for 21 years and has only had sex with one other person during that time. One who I've known for a decade and who, like me, is very choosy about partners and is only sleeping me with and his current girlfriend and they've been together a year or two. And one, who I met here, who has been my lover for three years and who is only sleeping with me. I trust these men completely and I'm not naive in that belief. I am a good communicator and openly discuss all sexual and health-related concerns with my lovers. It's about safety and responsibility.
Whenever I have oral sex with my lovers, I swallow every drop. And I do so knowing that it's perfectly safe to do so and enjoy pleasing my lovers.
But you have to be careful out there. If your partner has more than a few lovers, it's best to either drop them for someone who doesn't sleep around or to use condoms when performing oral sex. No man or woman, no matter how amazing in bed, is worth dying for. So play safe.