Why? Because your skin, as well as products like soap and body wash, serve as food for mold. That means, in turn, that every time you wash yourself with that puff, you're scrubbing your skin with mold. Lovely thought, isn't it!?
Clean it up: Wet the puff and microwave it for 30-60 seconds. Yes, microwave it!
7. Also that loofah
The exact same thing applies to that loofah that's hanging out in your shower caddy -- it's almost certainly harboring a ton of bacteria. Make sure to clean your body-scrubbing tools at least once a month to keep cooties at bay.
Clean it up: Use the microwave method, or throw the loofah into the washing machine with a load of laundry, or run it through the dishwasher.