Due to the amount of sweat glands in our feet, when we are hot, it's going to be one of the first places we try and lose heat from. This is from a process called evaporation. As the sweat is excreted, hypothetically, so is the heat from the moisture as it evaporates.
However! Most of the time we are wearing shoes of some kind. Now this poses a problem. If we are wearing shoes, there is no place for the evaporation to occur. Now our enemy 'bacteria' loves to thrive in warm moist environments. So if your feet are in an enclosed environment, then there will be a build up of warmth and moisture. Now it's not unusual for bacteria to find its way to your feet, because bacteria is literally everywhere. It's just that we are able to wash it off everyday, so that there is not a build up on parts of our bodies.
Now the problem lies here. If you tend to wear synthetic socks or shoes, this does not allow your feet to breath, or sweat to be absorbed. Instead, the sweat remains within your shoes or socks, and they start breeding bacteria, and this is what causes the horrible smell, that some of you may be familiar with. An interesting piece of information is that the bacteria which causes your feet to smell, is related to that of the bacteria which commonly causes acne (I have absolutely no idea why), but it's true!
It seems once your feet start to smell they don't seem to stop. They just seem to get worse. This may have to do with a fungal infection that you may have picked up (as fungal infections love anaerobic environments - e.g. an environment without oxygen). Which is often the case with your feet, especially if you are using products that do not allow air to get to your feet; such as synthetics, these kind of products do not allow your feet to 'breathe.'
It also seems that once you have foot odour, it jumps from shoe to shoe, and by this stage it doesn't seem to matter whether you are wearing synthetic shoes or leather. It only just gets worse!
Firstly you need to throw out those shoes affected by the smell, even if they are your most treasured pair of shoes. If you keep one pair, they will just infect your new pair! So if you don't do this to start with, the problem will continue.
Next you need to find some anti-fungal cream, in case you are suffering from a fungal infection, keep using it for as long as required (the product will tell you). If you find your feet itching, it is normally a telltale sign of a fungal infection.
Now you need to go out and buy a heap of cotton socks. Cotton allows your feet to breathe naturally. It also absorbs sweat really well without odour. They are a must!
The other secret is to buy some heavy duty, odour absorber innersoles. These are the final trick to beautiful smelling feet. They absorb sweat, so that there is less chance for a moist environment for bacteria to breed in. You must make sure to put then in every pair of shoes to make this system effective.
When you are at home try and avoid wearing shoes full stop. This will allow normal evaporation of sweat to occur, so that evaporation will take place, and no moisture is on your feet to breed bacteria in.
Oh, and try and give your feet a footbath once a week. It is not only relaxing, but it is effective in taking off dead skin cells. Soak your feet, and then use a foot puma's stone to scrub your feet. Let them dry and use a non-scented light moisturiser. Try and leave your feet open to the air that night.