Maybe this is more true of countries like India, where I'm from, where I can imagine hygiene standards being more "flexible". But here in Western Europe for example, or the US, airbnbs are almost better maintained than I'd maintain my own house. And I think there's a good reason for this: the impact of reviews. Even in India, I can't imagine a place going far looking like a cheapo dorm room, because people will definitely look at reviews.