Save Your Shoes – Moisture from perspiration or mud puddles is tougher on the leather than pounding the pavement. If shoes get wet, stuff crumpled newspaper into them to wick up moisture. Another suggestion is to put a charcoal briquette into a sock and put that in the shoe overnight to both absorb wetness and eliminate odor.
I am a great fan of natural lemon grass oil. Put a few drops of lemon grass oil on the crumpled paper or the charcoal briquette that you put into the shoe. This oil will give the shoe that nice fresh smell and help take away that sweaty moldy smell.