I have a favorite hat. It's really been through a lot over the years. One thing I hate is getting the sweet stain circle around the headband area. To clean your baseball hats and remove the stains first pretreat with liquid laundry detergent. Soft hats can be then thrown right in your washers. Wash on the gentle cycle and air dry. Do not use your dryer, it will shrink and possibly destroy your hat. For shaped hats, you have to support them before laundering otherwise they will completely loose their shape. You can use two strainers and press the hat between them. Tie the strainers together and launder.