Do not use baking soda on wet shoes, and be careful with leather, since too much can dry it out over time. Sachets are the safer choice for leather. Never mix it with vinegar inside the shoe, since the fizzing can leave residue and wet the material. If your shoes still smell after several treatments, wash them as the care label allows, remove the insoles and dry everything in the shade. If the odour is stubborn, or your feet have skin problems, redness or signs of infection, speak to a doctor or podiatrist, because baking soda cannot treat a foot condition.