The ears of dogs are warm and moist. This's the reason they're breeding grounds for bacteria, yeast, and ear mites. It is, thus, vitally important you ensure that your dog's ears are kept as clean as they can.

It's no fun to get hold of an ear full of earwax. Less fun is whether the earwax forms a hard plug type object next on the eardrum. This involves medical attention, making sure that a doctor is able to remove the plug.