I can make that distinction for you, David. if I was offered a lens and it worked fine I pay "the going rate" for it. If I was offered a lens and it worked fine but internal damage was disclosed, I pay 50% of the going rate for it. If I bought a lens that didn't work fine (or as advertized), then I'd demand a 100% refund. If I bought a lens that worked fine but later discovered hidden damage that was not disclosed, I'd not only demand a 100% refund; but I'd make it know far and wide that a disreputable transaction happened. If I bought a lens that worked fine but never discovered hidden damage that was not disclosed, then we all sleep well at night... or do we?

Does that help claify this ethical dilemna?