Think of charcoal and you may picture briquettes in your Weber. But pump oxygen into those same black lumps, and you have the porous substance — activated charcoal — that's now in a slew of skin-care products. "Activated charcoal has little holes and picks things up like a sponge," explains New York dermatologist Whitney Bowe. Use a soap or shampoo that contains the stuff and the charcoal particles will pull dirt and bacteria out of the pores of your skin or scalp before getting rinsed away. (Just don't go overboard; using multiple products a day can strip oils from skin.) Here are four products that do the dirty work.