1828 Half Dollar

Of course not. A cleaned coin preserved for posterity is miles better than none at all. All the same, we (numismatists) have generally adopted the standard that cleaned coins carry less intrinsic value than original ones. I agree with that standard.

But if someone "operates" on the coin, achieving an original-looking coin that not even the experts can discern, well, that's OK too.

If you can't tell it's cleaned, is it really cleaned?