So yes, I suffer with stinky feet. Washed several times a day, breathable shoes and socks, I've tried most things. Seems to run in the family.
My new, leather sandals have already started to smell. In desperation, I sprayed them with the Hg odour eliminator for surfaces. We use it normally for DC's wee accidents, or vomit. It has an enzyme in it that breaks down the nasty smell.
Well, knock me down with a feather, it only worked on my stinky sandals!! Not a whiff, no discolouration, happy, happy happy!!!