not only does it make your toes stink, it makes you generally vulnerable to skin yeast infections, it distorts the growth of the nails, which can lead to chronic problems with pain walking.
i had this problem for years, and i saw many muslims in prison in bulgaria (illegal immigrants) who had really nasty smelling feet because of their 5x daily washing and then wearing the same dirty socks and shoes day in day out.
i had to take a really aggressive approach to it, got a nail brush, scrubbed the hell out of my noes and whole feet until there was no excess skin.
i don't have any problem with it now.
and this is a problrem you, as a father, can do to help your son.
Jesus washed the feet. You should wash the feet.
it's the easiest way to make sure it's clean. If he prefers, get Mom to do it, whatever it takes to let him have clean feet.
the other thing, buy an excess of socks, and at first bleach them frequently so they aren't carrying spores to reinfect.
it's an almost universal problem for men, the toes and the nether regions to not be properly cleaned. cleaning the rear parts also... it really helps a lot and as the bulgarian practise goes, there is special hoses that i've heard a guy from new jersey refer to as "butt guns" that do a great job of making sure there isn't any smell there either.
it's also something that high carb, seed oil ladened diets make worse by adding oxidation prone fats to the skin oils.
i'm pretty passionate about this stuff because i suffered quite badly with it.
i can't stand the smell of perfumes, and people would often insist i use them and my response was generally to increase my washing regime.
in the last few years, though, i've seemingly been surrounded by people who seem to not value good hygiene. the deprecation of bathtubs, which are not only a great way to get washed, they loosen the skin and help you exfoliate better, and at night, when you are having trouble sleeping, the heat slows down your metabolism.