What attitude do you take to people who put on slippers as soon as they get on the train?

I will look down on people who take off their shoes on the train. I think this kind of person has no quality, because the train is a public place, and it smells bad when you take off your shoes. Once when I came home by train, a man across the street took off his shoes and put them next to me. It is in summer that there are many trains. I feel particularly bad and hate this kind of behavior.