The hook-and-loop fastener looses its efficiency when it gets soiled with dust, hair and lint.
First, wash the hook-and-loop fastener with warm soapy water to clean grease and dirt. Then take a fine-tooth comb and start combing out along the rows in one direction.
The rest can be removed easily with your fingers or tweezers. You can comb out the dirt with a stiff toothbrush or any brush with hard bristles as well.
Always keep your hook-and-loop fastener fastened when washing garments or shoes. To decrease the number of dust, spray the hook-and-loop fastener with antistatic spray.