Kitchen sponges. Those who use them love them. Those of us who are trained in microbiology don’t. Why not?
The simple answer is: because they remain wet. Bacteria love to grow in damp places. During COVID, I had my students do an experiment in their homes, checking for the germiest (scientific term) places. If you want to try it, here’s the book.
It wasn’t the toilet seat, the light switches, or even their cell phone. Their water bottles and the kitchen sink were pretty disgusting. But, if they had one, the germiest place by far was the sponge.
Some people try to clean the sponge by microwaving it, filling it with soap, or putting it through the dishwasher. These methods don’t work, as you will be aware if you smell it the next day. Why not? Germs grow fast. (photo from Wikipedia) If even one is left alive, after only five hours, it could be 30,000.
You may be asking if it’s possible to clean the offending object. Nope. Sponges are cheap. Throw it away and buy another.