Why is it so important for bedrooms to be spotless when visitors don't see them?

Asking as a grown ass adult who pays rent but still has to live at home. And I don't mean dishes and food and trash lying around. I mean why does it have to be spotless, no clutter, no clothes anywhere. My entire life is contained in a 9x9 space, how am I supposed to not have piles of clothes or books or merch or plushes showing? Especially when the only other person that sees is my mom when she's trying to make it spotless in there