Thats normal They look clean to me ....Go spend them .... Is it worth all the time and effort to clean them any better...
An hour in the tumbler or 10 hours they will always come out the same so why spend that much time on them. If you want them to shine then hand buff them for an hour each.... Would you spend an hour cleaning a clad Quarter ?
Get the majority of the dirt off and let the public clean the rest in their pockets.