"The skin secretes antibacterial substances. These substances explain why you don't wake up in the morning with a layer of mold growing on your skin - most bacteria and spores that land on the skin die quickly."
Wow, I just never thought about why I don't wake up in the morning with a layer of mold growing on me. Good to know I don't have to worry about that.
Note: that quote is from Bodyworlds (WARNING: this site contains pictures of anatomical exhibitions of real human bodies).