Some really nasty foot odors are caused by bacteria that colonize the shoes & are transferred to the foot. Wash affected shoes in mild bleach solution in washer. Rinse feet in peroxide while standing in shower. It kills the odor causing bacteria. Do it daily until you've cleaned all pairs of malodorous shoes.
If bleach sounds too harsh, you can rinse the inside of the shoes with peroxide & let dry thoroughly before wearing.
