From what I've seen, I'm pretty strict with anything sexual, actually, very strict. If I'm going to do something that exchanges fluids I need to:
1. Trust the person to be honest
2. They must be tested.
3. They must not be involved with anyone else who has not been tested.
4. I must trust anyone else they are involved with who has been tested to not get involved with others who haven't been.
I know this is very restrictive, and I make sure anyone I get involved with is okay with this beforehand. We make sure any new partners are on board as well, I don't want to impose this on anyone unless they willingly accept it coming into a relationship with one or more of us. And while I know protection is an option, and a good one at that, it simply is not fullproof enough for me to be willing to be with someone who has sex with untested partners but uses condoms. I also REALLY detest condoms. I'm on birth control for a reason, and would rather not have sex at all, then to do so with a condom. If ever my partner wanted to play at a play party or event I might be willing to negotiate a one time thing where condoms were used, and that partner refrained from contact with any of us until enough time had passed and they were tested again though. Even then, its iffy, cause you can still catch something if a condom breaks during an infrequent playtime with someone. Honestly, my rules may be tough, but I'm just not willing to take the risk with my health and that of those I'm with, and if others cannot respect it, they don't need to get involved with us or can find ways to do so that do not involve fluid exchanging activities. This is what we are all comfortable with, so we stick to it.