No, wool dryer balls do not leave wool on clothes. The purpose of the dryer ball is to help reduce drying time and static cling by separating clothing items in the dryer. Wool has been used for centuries as a fabric softener due to its natural lanolin content which helps soften fabrics without leaving residue behind. Even if most Wool Dryer Balls are lanolin-free, it's still the best alternative to dryer sheets. Additionally, when using wool dryer balls it is important to use ones that are made from 100% pure sheep’s wool with no added synthetic fibers or chemicals so that there will be no risk of leaving any residue on your clothes after washing and drying them.