I don't know if this topic has been discussed before, as I usually only read the silver or copper threads... but does anyone know if the process described in the linked article would work on silver coins without damaging them? Think of the potential of ebay sales if an opportunistic seller did a bit of research on the recoverability of obliterated dates without damaging the coins? You could market a bunch of total slicks as potentially containing great rarities you could then specify. Of course, you would mention that doctoring coins can lower their value... but c'mon... if you have the possibility of possessing a high-dollar coin in ANY grade (and remember, its just a slick now) wouldn't you jump at it? See article that is linked:
http://www.csudh.edu/oliver/demos/buffnick/buffnick.htm