I read this entire thread under the assumption that we are talking about long term partners here. Completely disregarding HIV, there are enough other STIs that say unprotected sex is a bad idea, so if we are talking about hookups, the person can tell me whatever they want, condom is mandatory.

Of course long term relationships don't magically shield you against STI, but I'd hope there is enough trust to share test results of any kind that are relevant to this matter if you are having the discussion about going fluid bond. And you probably know the person well enough to know if they are reliable with taking their meds on time.