Best bet is to check with your vet. 'Nasty' ears could be a sign of infection and should be treated immediately otherwise it can lead to broken eardrums, and painful hematomas. Some cleaners work good for some things others don't and at the worst end some just make the problem worse.

Not knowing what is causing your dog's ear problems I can't recommend any particular product. Your vet is in a much better position to answer that one for you.