Foot odor (or foot odour) is a type of body odor that affects the feet of humans and is generally considered to be an unpleasant smell. Cause The main cause is foot sweat (also see focal hyperhidrosis). Sweat itself is odorless, but it creates a beneficial environment for certain bacteria to grow and produce bad-smelling substances. These bacteria are naturally present on our skin as part of the human flora. Therefore, more smell is created with factors causing more sweating, such as wearing shoes and/or socks with inadequate air ventilation for many hours. Hair on the feet, especially o...