If your not throughly tired of this thread by now. Throw away your sponges. Replace them with hand rags that you launder.
Sponges are bacteria factories.
Moist, lots of surface area, bits of this and that wedged inside the spaces. That sour smell of a unwrung out 10 hour sponge comes from bacteria inside. Commercial food establishments don't use sponges as cleaning implements, and you shouldn't either. In fact, its a violation of WA state food law to have a sponge in a commercial kitchen. Its something the inspectors look for.