My doubts that the vet did anything but administer the treatment, most vets do little grooming except shaving animals badly matted. My cat had ear mites very badly one summer and has left him with chronic ear infections ever since, so yeah that black nasty ear gunk definitely needs to come out. Give your vet a call or read the bottle of any ear drops he gave you, a lot of them say not to clean the ears for a certain amount of time, so it can to fully work through and kill the ear mites.. It will take more than a days work to be able to get out all the gunk, and usually the ears will become sore or irritated if cleaned every single day, so try every other day.. Cotton balls work great but its hard to work around really well, especially dry. My best recommendation would be plain old pre-moistened ear wipes. They are very cheap and come in packs with pretty good numbers, they are easy to get around the ears, and pick up more in less time with less irritation. That way kitty might not think its such a bad thing lol. Good luck though I hope your kitty gets to feeling better.