> The difference might be that shoes aren't as good of a substrate for bacteria as a warm moist foot.

Oh, good point. I hadn't considered that.

> The athletic administration at my college required that I put my shoes back on when practicing soccer on the intramural fields. Their reasoning was that I could get a cut and develop an e coli infection.

This is also a good point, but not the issue that was being raised, which was specifically about others' health, not my own.