Keep your kitchen sponges clean, bacteria-free, and smelling like nothing at all with this handy trick. Once you're done cleaning with the sponge, wring it out and set it in a window. The sunlight will dry the sponge out and kill most of the smell-inducing bacteria. I prop my sponges up so that only one small edge is touching and all the large sides are exposed to air. This method works much better than chemical or microwave-based approaches. I have literally used a sponge until it shredded and it never smelled bad.