Honestly probably the best written post I’ve seen on Lemmy.
Any house with a toilet is covered in a micro layer of shit particles so most likely.
Do you press your mouth against the toilet and flap your tongue around on it?
They only really covered STIs. But there’s a huge range of things in your mouth. Colds and flus are big ones obviously. But also things like mono etc.
Any exchange of fluids is a risk. Just have to be as clean as possible and choose your partners well.
In that second comment they talk about the normal stuff that comes with oral/vaginal and how it’s not like what’s in/around the butt. STIs are called out as an exception, they aren’t what the comment is really about.
The jist is that you can get some temporary inconvenience with a new partner, but it’s unlikely to be anything serious.