I struggled with foot odor my whole life so know the plight of smelly flip flops. I recently found a natural product called Lavilin Foot Cream that has really worked wonders. It seems to actually attack the cause of the odor instead of just covering it up and neither my shoes or flip flops smell like they used too. Being of hippie parents I also really love that it is all natural and not filled with chemicals like most deodorizers.