If your Fitbit stinks, it is likely due to sweat, dirt, and bacteria accumulation on the band. To prevent this, it is important to clean your Fitbit band regularly and avoid wearing it in water-resistant conditions, such as during hand washing or swimming. Also, avoid using hand sanitizers or high-intensity workouts while wearing the band. If the smell persists, you can also try using a gentle skin cleanser or applying a small amount of baking soda to the band to absorb the odor.