Bike touring can be a sweaty and smelly business below the knees. By their very nature motorcycle boots are hefty items and even the very best vents and breathable linings will struggle when the temperatures or humidity rises.

A build up of bacteria creates a stomach churning stink that talc and charcoal inserts just won't shift.
 
The solution is vodka. The concentration of alcohol in Vodka is high enough to kill the bacteria but has no predominant aroma making it an ideal sterilizing liquid.

You can wipe your feet over with a vodka soaked paper towel or if the smell is particularly bad you can soak your feet by pouring a couple of glugs in a plastic bag. Give the inside of boots a wipe inside with a soaked paper towel but be careful to avoid delicate waterproof membranes.