First of all, as to the most obvious ailments fo barefooting cuts and bruises, feet tend to be tougher than we give them credit for. I think this can only be effectively learned by experience. In a over a year of barefooting, I can count only a handful of superficial injuries. The worst of these was stepping on a cactus, which, in retrospect, wasn't that bad. Second place injury, I hit my heel with a door, but that could have happened had I been wearing sandals.

I can't say much about the dirt and bacteria I am dragging around. Maybe that would be a study worth doing aided by someone in an appropriate field of expertise. But by visual inspection, my feet are generally cleaner when I don't wear shoes (unless I walk on asphalt, which makes them turn a rather unplesant shade of black) and (again, visually speaking) they are DEFINATELY cleaner than my shoes ever were. If I step in mud, it wears off in a few steps rather than getting hopelessly embedded between in the rubber material on the bottom of the shoe put there for traction. Besides variable terrain, which scrapes off old dirt while depositing new dirt, the sweat of my feet serves to wash them, rather than festering with the result of stinky socks.

Finally, I have never been a fan of gayly galavanting through waste matter of any kind, shoes or no. Nor am I a particular fan of pigs. I do not know anyone in my neighborhood or any other place that I frequent who keeps a pig as a pet, so I think this scenario abominably rare, if not utterly impossible.