Ferrets collect ear wax. It may be a hobby or it may be due to the fact that they are low to the ground and so collect plenty of dust and dirt in their ears. One thing that is known, however, is that ear wax contributes to the ferret's overall odor. To keep your ferret in tip top condition, you must clean their ears every so often.
WHEN? Some ferret owners recommend bi-weekly cleaning, others recommend monthly, and still more recommend cleaning every other month. To me, how often you clean the ferrets ears should depend on the ferret. Some ferrets can go one or two months without having their ears become overly filthy, others can only go two weeks. I was so concerned about the rate at which one of my ferrets was building ear wax that I have had him checked for mites more than once; mites have never been found in his ear wax - he is simply a waxy ferret, and he needs his ears cleaned more frequently than any of my other ferrets.
HOW? Scruff your ferret, dampen the end of a Q-tip or piece of gauze in warm water and gently clean the gunk out of the ferrets ear. Be sure to only clean where you can see and STAY OUT OF THE EAR CANAL - you don't want to damage your ferret's hearing! Use as many Q-tips or as much gauze as necessary to clean the ear. Do not try to save on Q-tips or Gauze by re-using dirty, contaminated pieces. Alternatively, you can try using ferret or kitten ear cleaning liquid or mineral oil to clean out the ears. If you do use such products, I recommend warming them first by immersing them in warm or hot water - most ferrets will protest slightly less to having warmer liquid put in their ears than ice cold liquid. Additionally, if you use chemical products or even natural ear cleaning products, be sure that they are ferret-friendly so that they do not damage the ferret's sensitive ears and keep in mind that 'natural' or human friendly does not necessarily mean 'safe' for your pet.
WHAT WAX LOOKS LIKE: Brownish, varying in shade from light to dark. Things to watch out for: black wax, crusty ears and coffee ground deposits in your ferret's ears, all of which could indicate the presence of ear mites.
ABOUT EAR MITES: Ear mites are more than just a minor irritation for your ferret; they can cost the animals their hearing. If you believe that your ferret has ear mites, DO NOT simply get treatment from your local pet store as it has been found that the wrong treatment can actually not only damage the ferret's hearing, it can actually burn the animals! A vet visit is usually the best way to deal with ear mites, and remember if one pet has mites, chances are all of your pets have them! Avoid using Oterna ear mite medication as this has been found to harm the ferret. I have personally had success with using half a tube of pink kitten Revolution on my ferrets to rid them of fleas, ear mites and intestinal bugaboos. This is technically an off label use, so be sure to ask your vet about it. Finally, do not rely on mineral oil or baby oil to de-mite your pet ferret as though this stuff can drown many adult ear mites, it does not kill the eggs and has not been found to effectively eliminate all adult mites.