‘Toe jam’ is not exactly a medical diagnosis and is a lay term for that yucky stuff that can build up between your toes and can have a foul odor. It is not pleasant to have or to talk about it.
Toe jam is a collection between the toes of a number of things that include dead skin cells, lint from sock and other debris that get moistened by the lack of evaporation of sweat between the toes. It is going to worse in those who have shoes that do not allow the sweat to evaporate (which they may have to wear becasue of their work); those who do not clean between their toes and dry them thoroughly; and those who sweat more. It is important to differentiate the regular toe jam from a fungal infection (tinea) and maceration which is an accumulate of moisture in the skin.
The best way to deal with toe jam is to clean thoroughly between the toes and then dry them carefully and do it every day. Surgical spirits is an evaporative agent and can be put between the toes to dry them even more. Going barefoot as much as you can will also allow air to circulate between the toes.