Feet can smell as the foot sweats and its trapped inside footwear. It is the interaction of these two factors along with bacteria that cause the smell. Feet have more sweat glands than any other part of the body, so they can sweat profusely which can not evaporate (like it can on the hands) due to being enclosed in footwear. The bacteria produced is ovaleric acid which is what causes the odor. Each and everyone of our Acor shoes, Sole Defense Orthotics, and Sole Defense socks, contain X-Static silver fibers that fight and destroy the bacteria that cause odor. Our orthotics have a top cover with X-Static that give you even more protection.