The Unclutterer blog offers a smart way to separate your kitchen sponges into various roles. A reader there writes:
In our household, we discovered a trick: the Good Clean sponge [for dishes]is used as-is, straight out of the package. When it gets downgraded to the Wiping Sponge [for kitchen counters and the table] , we cut one of the corners off. When the sponge gets downgraded again to a Skunging Sponge [the dregs of cleaning] , we cut another corner off.
Sounds like a great way to make sure you're not using a skunky sponge on your cereal bowl.