We had trouble with Abbey at first when we got her--those long hound ears!!! One dose of the meds, and a vigilant cleaning schedule keeps it away.
Jada's ears get really bad too. Just last week she had a small infection, and a few drops from the vet cleared it right up (sorry, I can't remember what they were called).
I clean their ears every other day, with the wipes or with the liquid that goes into their ears--they hate it, but they hate the infections even more!!!

My boys, on the other hand, always have sparkling clean ears!!!