When excessive perspiration from your feet absorbs into shoes and socks, it creates an optimal environment for the bacteria to grow. This can be the cause of odour in shoes. Bacteria doubles every 20 minutes at room temperature. In an environment like shoes, which can be warm, dark and moist, bacteria might multiply at an uncontrollable level. It is advisable to keep footwear bacteria-free at all times especially if you suffer from this problem.