Foot odor is caused by bacteria from fatty acids deposited by our sweat. Our feet sweat throughout the day and the fatty acids they produce decompose making stinky feet.

The key is try and keep your feet dry. When I was working long hours underway I had to air my boots out every night and soak my feet warm water and antibacterial soap. I have never heard of using bleach but If I was sweating extra hard that day I would sometimes find time to switch out my socks.

Hope this helps