Bacteria and fungi love moist, dark environments. If you take off your shoes and immediately toss them into a dark shoe box or closet, you are putting your shoes at risk. It is important to store shoes only after they are completely dry. Once dry, use a shoe rack to store your shoes in a way that keeps air circulating to reduce the risk of bacteria growth.*
Keeping your shoes dry will prevent the kind of bacteria that causes bad odor. To dry your shoes faster, take out the shoe laces and lift the tongues up.
Photo | Travis Crawford | shoe rack hack | Used under a Creative Commons Attribution Share-alike License | Cropped