Try pouring baking soda in them and leaving them for a few days. Then pour it out. This always helps with my daughter's stinky shoes.
This link may help:
Sprinkle baking soda into the shoes.
I would add baking soda to them and then put them in the bright, hot sun for a few days, but bring them inside from dusk to dawn. You don't want them to get damp.
Yes, baking soda sprinkled into the shoes should do the trick. dump it out after several days and that should be that. Fresh air and sunshine helps.
a few drops of essential oils may help too....
Sprinkle baking soda inside the shoes and change it every day over a few days.
I have bags of bamboo charcoal that I keep for stinky sneakers. You recharge them in the sin.
Got to ask first, why do they smell like moth balls in the first place? Two things that work are newspapers and sunshine. Both take odors away. Remove laces and let in sun for a few days, newspaper crumpled up absorbs odors.