When wearing shoes over a long period of time, or even during rigorous physical activity, they can begin to build up unpleasant odors. These odors are caused by bacteria. During daily wear, feet will sweat, often soaking into and through socks and into a shoe's insoles. Once there, the shoes provide an excellent breeding ground for the bacteria that give shoes that nasty odor. Using a few basic preventative steps, most cases of bad shoe odor can be eliminated without destroying the shoes.
Use Sperry shoe freshener on the inside of the shoes, ensuring to spray the entire insole all the way into the toe, following the directions for application to achieve the best possible result.
Rotate between different pairs of shoes daily. By not wearing the shoes consecutively, the bacteria within has time to dry out and die off, preventing the odor from building-up.
Wear clean socks constantly. Dirty socks have bacteria already built up, and will contribute more to the problem. This bacteria can be transferred to the insoles of the shoes, where it will spread, and cause bad odors, and even cause rot and decay over long periods of time.
Pour some baking soda into a cloth. Fold all four corners together, and use the string to tie it up. Put the newly made satchel into the shoes. This method allows the baking soda to absorb the odors in the shoe without causing possible damage to the shoe fabrics.