I'm no barefooter but I would argue the complete opposite of what you've said. Serious infection and bacteria are spread around via touching something that is infected or laden with bacteria. Unless someone is rubbing their feet all over you, the fact that someone is barefoot won't promote the spread of anything. In fact I'd say their feet are probably cleaner, in the bacteria sense, than someone like myself who wears socks and shoes and allow their feet to swim in sweat all day.
Does the way I started this irk you YorkVol?