Gold Bond powder. Sprinkle in a little every time you wear therm. You'd be surprised how many sneaker type shoes (trainers, jogging shoes, etc) can go through the washer, even if they are leather. you can actually tear the insole out of shoes and put a new one in every few months. But mostly use the powder.
Thanks for all the advise. Lately, I've been wearing socks and it hasn't been that bad. They don't smell too bad. but if I wear them with my feet "which normally don't smell that badddd" after a few hours or so, than they smell. I just put baking soda and some golden bond powder in a bag and put the shoes in there. I put the entire bag in the refrigerator "lol". I'll keep them in there for awhile. I might have to put some power on my feet when I wear them without any socks.