Sweaty feet (hyperhydrosis) and smelly feet (bromohydrosis) are two very common, annoying conditions of the feet.
Some cases of excessive smelling or sweating of the feet are systemic (throughout the whole body) in nature, such as anemia (low blood count) or hyperthyroidism (overactive thyroid). But most cases have a "local to the foot" cause.
For instance, wearing shoes that have synthetic materials, and socks that are of man made fabric can both contribute to the production of excessive perspiration and the bacteria growth that causes this condition. These two conditions set up a condition called athletes foot (tinea pedis). Unfortunately, most shoes are made of synthetic materials, especially tennis shoes, so if sweaty/smelly feet is a high concern, you will want to be especially careful when shopping for shoes.
There are a host of medications, lotions, powders and creams that are effective against these conditions. Oxistat is an excellent medication for tinea pedis. Bromi Talc and Bromi-lotion Anti-perspirant are excellent for sweaty or smelly feet. Paraffin bath treatments are also helpful in reducing the level of perspiration of the foot.