Any tips on how to get my German Shepherd to let me clean his ear?

[BlueKota]

He let's me clean the left one bur not the right one. He actually tried to bite me a few times when I attempted it and normally he is a big loving goofball. I have tried a few different muzzles but he's smart and fast, and gets it off before I can get the cotton ball with the cleanser in far enough.

He's also getting a little growly when his groomer tries to buff his nails on his back right hind leg after trimming them, and he did it to his vet as well, when she was examining that same leg.Didn’t go for a bite but just gave warning growls. We are going to drug him the next vet visit, and have her check the leg then. This part makes sense to me because he was injured before we got him. The breeder was walking the mama and puppies along a river bank and Dakota tripped and fell of the bank. He hurt that bad leg and to make it worse the emergency vet he was taken to misdiagnosed him, and a second vet the groomer took him to did the same.

I got him at 4 1/2 months. He is going to be 5 years at the end of this month. Our vet caught the misdiagnosis and even confirmed herself with a friend of hers who is one of the head radiologists at Cornell. At the radiologists suggestion our vet put him on Dasuquin and he gets one every day. He doesn't seem to favor that leg, and doesn't mind me, my sister, or my cousin touching it, but my guess is it's arthritis from the old injury setting in. Will have the vet confirm.

But I'd rather try to see if there's a way to get his ear cleaned sooner, because I don't want to put him through too much at once at the vets' office because even with being drugged he is a nervous wreck, and I don't want to prolong the trauma for him.