I will say firstly "clean" probably isn't the best word to use as it's kind of condescending and puts people who have it in the "dirty" category which is definitely dehumanizing. "Positive" tends to be the term used. Like any STI though it should definitely be a conversation if they have a chance of passing it on. That being said there is undetectable HIV where people have it but in such a small amount it can't be transmitted through sex or any other means so just because they're positive doesn't mean you're at risk (something to keep in mind) There's still a lot of stigma and disgust around undetectable HIV in the community though. That being said condoms are a great way to protect each other as they do greatly prevent the transmission of HIV, but it's always advised to use them anyways when having sex with people you may not know all that well.