If you think your cat’s ears are grubby it might be temping to clean them out with a cotton wool bud. However most vets would advise you to not to tamper with the ears at all as the tissues lining the ear canals are very delicate and easily damaged. Ears may be dirty because there is wax but it may be caused by ear mites or a skin irritation.
Check with your vet who may give you a product to wipe out the outer ear but avoid going too deep into the ear and causing more damage. Please watch the video above for information on how to clean your cat's ears.