Simple solutions can help clean your cat's ears.

Ruby and her cat Patience learn how to clean cat's ears. Patience is 18 years old.
The best way to prevent another painful ear infection is to routinely check the ear to make sure there’s no redness, residue, or odor. Healthy ears are pale pink and have no visible debris or odor and minimal or no ear wax. It is best for the veterinarian to show you how to clean your cat's ear or to do it himself or herself. Never insert a cleaning device into the ear canal itself unless your vet has instructed you to do so.
You don't normally need to swab your cat's ears, but ear mite treatments usually require cleanings.
Most cats do a great job of keeping their own ears clean. Their grooming habits are so meticulous that they will even clean behind and in the inner flap of the ears. However, cats will sometimes need help cleaning their ears. It's also a good idea to frequently check your cat's ears to look for problems lurking inside the ears that could become more serious. of How to Clean Your Cat's Ears was reviewed by  on January 3, 2017.Below is an excellent video that shows how to clean a cat's ears:Secondly, do you yourself clean your cat's ears consistently? Do you know how to?
It can be ear mites. Are they scratching? Get them used to getting their ears cleaned, be firm but gentle. Take a clean kleenex, fold it, wrap it around your finger and gently but firmly wipe the junk out of their ears, getting new tissues frequently to avoid spreading the black stuff. If you are careful you can get down into the smaller section of the ear safely, but don't go any further than that. if it is ear mites, don't come in contact with them, they seem to have 2 inch long fangs! They burn when they come in contact with our hands-and with the cats ears. If you have more than one cat, clean all of their ears, it can be easily spread from one cat to another. It will take several cleanings to control it, first every other day. If it's really bad, then once a week, then once a month. We had a cat who had it chronically and she would come and ask us to clean her ears. Most cats don't like it done, but she really appreciated it. Any cat who has a bad case of ear mites gets it that the cleaning makes them feel better. There's a liquid wash you can get from your vet that helps clean their ears.I agree it is likely ear mites. You have to take your cat to the vet, who will show how to clean the ears and give you medication to kill the ear mites. Go now, before the cat scratches its ears raw on the outside.That black ear wax is not ear wax. It's ear mite poop. Clean the ears with a q-tip without going inside the ear. My husband used to instruct clients to "use it like a spoon" and scoop the crud out. Then with a cotton ball moistened with alcohol or just water clean them the best you can. If you use ear mite medicine on top of all that stuff you'll just have medicated poop and won't kill the mites. Go to you vet office and ask for ear mite medicine. Don't rely on some of those Walmart things and certainly not Sargent's or Hartz. If you have money to throw away, throw it my way! You need to treat 3 times a week for 3 weeks to totally rid the cat of the mites.My cat had the same thing, but NO itching, so my vet knew it was not ear mites. Also, the flea meds I give him from the vet once a month also takes care of ear mites. The black crud Ramsey gets is just wax and my vet told me to just use a q-tip dipped in a little olive oil and clean the crud being careful not to dig deep. I do this at least once a month. Ramsey doesn't like it, but he's getting used to it and when we're done, he heads directly to the treat jar where he knows mommy gives him a treat afterward for being such a good boy.Sounds like ear mites. I had a cocker that constantly had them and her ear wax was black. You will have to go to the vet and get the cat medicine to clean the ears and medication also.It's your job to make sure your cat's ears are healthy and free infection and mites. Dr. Marty Becker shares how to examine, clean and medicate cat ears.