i saw a news report on this once and was so ill to learn of all the germs that live in our favorite cleaning friend 'the sponge'-- it's disgusting-- that and all the dust mites that live in our pillows. I replace my sponge quite often, and run it through the dishwasher regularly as well. It's still probably gross.. but as beatpoet suggests, a kitchen sponge is kinda like the elephant in the room!