A hat, especially one worn when exercising, can often become dirty and take on a foul odor. To remove this odor, the stinky hat must be cleaned. However, it is not always a good idea to wash a hat in the washing machine. This could cause the hat to shrink or become misshapen. If your hat has a tag that indicates it can be machine washed, you should be OK in doing so. If there is no tag indicating that the hat can be machine washed, you will have to resort to hand washing it.
Wash your hat in the washing machine if its tag indicates this is acceptable. Pre-treat heavily soiled areas by rubbing some laundry detergent over them.
Pour some mild laundry detergent onto a dampened cloth for use in cleaning hats that cannot be machine washed.
Apply the detergent onto a hidden area of your hat to make sure it does not affect its color.
Rub the soiled areas of your hat, paying special attention to the inner headband, with the laundry detergent.
Rinse the cloth out with water and wipe away the laundry detergent from the hat.
Repeat steps 4 and 5 until your hat is clean and no longer has an unpleasant odor.
Allow the hat to air-dry when finished cleaning it.