Whether we're talking feet, sox or shoes, it's not the sweat causing the stench, it's the bacteria that feed on the sweat. More specifically, it's the waste products created by the bacteria. EWW!
Washing the feet works because it removes the wastes and reduces the bacteria population. Same with fresh sox- less waste=less smell.
To go even farther, and actually kill the bacteria, try applying vodka or rubbing alcohol, either as a splash or with cotton balls. Works like a charm. My pedicurist says it helps with calluses, too, but I'm not so sure about that part. But it definitely helps with de-stankification. Feels good, too.