With the caveat that I generally try to follow the general social sentiment on personal hygiene, I think that smell, hygiene, and personal appearance are some of the more onerous class signifiers. The idea that human beings shouldn't...smell like human beings (?)...and that even otherwise based people will actively discriminate and dehumanize others in their mind because of hygiene is mind boggling to me. It's not a universal thing either, and people in nations that haven't largely accepted the universality of the western nose seem to be fine for being "smelly." There are obvious exceptions in terms of medicine and health, but in general, people are literal animals that evolved to be outdoor cats so to speak.