I use a small scrap of towel-- potholder sized. I pour on a palm-sized spot of witch hazel and then slowly, gently use that to wipe our the ear.
The witch hazel cuts oil and attracts dirt. Rubbing alcohol will work, too. You'll see the skank on your towel and get all satisfied. Her ears will look great and you won't have to do this often. I have not had problems with drying out the skin.
The small towel and a mellow technique will help her accept this to the point that she lets you put a towel-covered pair of fingers inside her ear near the bottom.
Don't attempt to stuff anything in deeper than the base. She'll probably show you the door well before you poke deep enough to risk hurting anything.
But many horses find that a towel on the inside of the ear higher up feels pretty good, so you might be able to start at the top and convince her to let you get to the part you want.
Thank you so much for the advice mvp. I doubt she will be too hard to clean. Although I've never clipped her, I can do amazing things with her ears and if it feels good at all to her she'll let me do even more. Thanks again.
I used a method similar to MVP's recommendation (less the witch hazel...wish I'd known that trick!) on a mare I used to own. At first she thought getting her gunky ears cleaned was the work of the devil, but eventually she realized it felt good to get the crap out, and she would put her head down and kind of "beg" to have it done. She was one of those animals that was constantly producing gunk--from her nasty, nasty udder schmega to her gunky ears, she needed regular maintenance.