Where is the line drawn when it comes to having sex in “common areas”?

This has been something that has puzzled me for a while. I frequently see posts on other subs (AITA especially) where people seem to be super upset by others having sex in shared spaces… for example, you have a roommate and find out they and their partner have had sex on the couch in the living room. The responses are always “that’s disgusting. It’s common courtesy to not have sex in shared spaces.” Or a post I just saw of a married couple having sex in the shower of a bathroom they share with others. On this one, it was a majority who were okay with it (although many were okay with it solely because they speculated that the couple was actually just showering, not actually having sex), but there were still lots of responses saying it’s gross and they would have to bleach the tub afterwards. It’s like having sex anywhere where other people might be is some kind of horrifying act and you need to bleach or deep clean everything because there was sex on it.

But like… where is the line drawn here? I personally wouldn’t have any problem with people having sex in shared spaces, as long as it was when no one else was home. If your housemates can’t see or hear you, and you clean up any mess, then what exactly is the problem? I feel like no one else shares that mindset though when I read these posts. The thing is, I have had sex all over my house. Sure I don’t have roommates, but still I have guests over. They have sat on my couch that I’ve had sex on. Is that not essentially the same thing? Am I disgusting? A heathen? Obviously if body fluids were to get on anything, I would clean that up. I’m not THAT depraved. I’ve also had sex all over boyfriends’ homes and we didn’t spend all day bleaching everything afterwards. And most people are fine with staying in hotels. The amount of crazy sexual acts that have occurred in any given hotel room is probably mind boggling. How is that any different?

I guess I’m trying to figure out if I’m just actually a disgusting person who is completely violating my guests by letting them into my home after I’ve had sex in it. Or if there is some kind of line that I don’t quite understand between having guests over vs having housemates. Or maybe these horrified individuals are actually a smaller subset of the population than my reddit readings would make me believe. And those of us who are not disgusted by this are just not as vocal. Thought maybe the people or r/sex would have some insight to share on this.