Interesting post about walking around barefoot... in the city.
Germs tend to not really be the biggest concern and if you can deal with the soot/dirt/dust that will inevitebly cover your bare feet, they claim that injuries from sharp objects tend to actually be smaller than with shoes on (their words, not mine). The thinking is, if you're putting your foot down on a piece of glass, etc you'll feel it quicker and instinctively pull back. If you're wearing shoes (That the glass/nail/whatever) can cut through anyway, you put down all your weight on each step regardless.
While I see what they're saying, I do think thats a bit of a stretch... Plus, I have really cool shoes.
Source -> http://www.popsci.com/science/article/2010-12/fyi-it-safe-walk-barefoot-new-york-city