Think this idea should be revisited, not so much in a smell'o'meter way but for health reasons. How many times have you been hit to bleeding point by zombies? How many scratches, scrapes and cuts would you obtain not just from zombies but from crawling through the mud (bushes, stingy nettles, etc), bullets, falling, paper cuts? And then crawling through mud would further aggravate the woulds by getting them dirty, leading to infection, leading to death. Having to wash every once and a while is a pretty realistic thing, it'd keep people moving, preventing people from indefinetly camping the airbases and such , forcing them into traveling to their nearest watering hole or face dying to disease