I have sweaty feet. I scrub, pedicure, polish and lotion. I keep my shoes clean and air them out between wears. Everything you are supposed to do in order to not have smelly feet - I do them all. But I still have smelly feet. Maybe not disgusting but enough that I do not share shoes and I don't like to take off shoes in public.
For me - I'd never kick off my shoe in public. Shoe shopping is a bit of a stress even. I have to assume that there are others people with foot issues out there and for that reason I do not like to see people getting super comfy and kicking off shoes and letting them rub against upholstery.
Still, the fact is you collect a lot of germs and grossness after a day at the mall. Trying on clothes, touching make-up samples, using the restroom, smelling a candle that probably 30 other people have already had close to their nose, sitting at a food court table that might not have been cleaned after the last person used it. Sitting on a chair where a person may or may not have had gross feet on it is probably low on the germ factor and I'd probably only think of it if I witnessed it.