Make yourself at home
We all understand that most people traveling home on public transportation have had a long, hard day at work. Perhaps they’ve been on their feet for the whole time, running hospital halls, or bringing meals to people with bells on their tables. They’re tired, and looking forward to getting home to put their feet up.
The important thing for them to remember, however, is that they need to wait until they get home to put up their feet. The seat opposite you on the train is not the place for your bare feet to rest until you get to your stop. Aside from the sanitary issues, I doubt you’ve paid for two seats.