by Gabe Mirkin, M.D., http://www.drmirkin.com/fitness/socks.html
The main purpose of socks is to keep your feet and shoes from smelling. Foot odor is caused by bacteria or fungi rotting old skin. Your skin turns over every 28 days. A new cell starts on the bottom layer of skin, then another skin cell forms underneath it. The process continues until the bottom cell reaches the top and is sloughed off as dander or dandruff. If you don’t wear socks, your old skin deposits in the shoes where it rots and emits an offensive odor. Socks prevent the old skin from getting into your shoes, and washing your socks gets rid of the old skin.
The bacteria that rot your old skin grow luxuriously when the skin is wet. If you have a problem with foot odor, try pouring a small amount of powder into the toes of your socks before you put them on will help to keep your feet dry during the day and prevent bacteria from growing. Avoid wearing the same pair of shoes more often than every other day so they can dry out between use. You can also kill the bacteria by applying a common deodorant containing aluminum chlorohydrate to your feet at bedtime and sleeping with socks on.