Perspiration is one cause of bad odours. To reduce bad odours you can use products that control perspiration such as Scholl Fresh step.
Scholl Top Tip
To control excessive perspiration, wear light shoes or sandals whenever you can and avoid synthetic materials - this allows your feet to breathe and stay dry.
Fish Therapy is an exfoliating treatment for feet, performed by fish in special tanks. It may sound strange but it's worth trying.