I too would like to see the obverse, and I'm probably alone on this (and may be wrong, but I've been right many times when no one else agreed - that's the fun in errors) but am I the only one that feels this was struck through cloth? My reasoning being: The areas where the portions of the letters are flat and NOT raised. These regions show metal flow and possible bunching if indeed struck through polishing cloth. Acid would not account for the metal flow between the M and A or the outlining around 1788. Yes acid can erode nice and uniform, but this looks clearly like pattern to me, especially since ints rounded with the contour on the legs. These areas in blue are strong fabric pattern to me. If the obverse is normal, I would take the risk and send it in for certification, or sell it to me.
I have a dime that I put on coin talk looks like your, no one said anything about acid but seeing your coin I guess that is why ??? Like you said very uniformed on my dime also.
Looks like sand/grit/bead blasting or a wire brush moved metal around. It is not a struck through. The rims are too distinct for it to covered completely by a cloth. However, Grit blasting or a wire brush would account for the metal flow and removal. It is not a mint error.
While metal detecting I've dug many clad coins, including a few that were really dirty and corroded. If this was such a coin and the finder attempted to clean it up, say with a brass bristle brush, he could get it to become very shiny (the nickel surface, if any remains), but ths surface of the coin, although clean and shiny would have yielded a very ripply , pitted and with much-decreased detail.
Sand blasting or a wire brush would never account for the raised metal contouring the date, hat, between letters, etc.
I recently found a bunch of nickels that look like that while coin roll hunting. Random dates and both mints. Out of an entire box of nickels I'd say I was getting eight to ten per roll. Looks like pmd to me but not a clue as to what caused it. It kinda looked like they had been hit with sandpaper.
It absolutely could, as the wires jump over the raised areas or if the shot was close to a parallel with the surface. I don't understand how a struck through cloth would leave the shadows. Google "struck through cloth" and you'll find coins with much less detail (polishing clothes aren't paper thin) and variable rims (caused by the cloth being uneven and pressing into the sides of the inside of the upset planchet as well as the top of the rim). I've attached a few photos from the first few to pop up on google. You'll notice that there is no shadowing or contouring of the raised devices, the rim thickness is irregular, there is significantly less detail than the OPs coin, and the fabric pattern is much coarser and shows much less distortion I would encourage you to google them yourself. For now, I'll respectfully agree to disagree that it is a strike through. There are a number of very knowledgeable error specialists on coin talk and I haven't seen any comments from them yet.
Not too bad. If this coin was dug, it possibly was part of a "pocket drop", where coins lay in the ground, in a stack, so that one side may be protected and the other exposed to corrosive processes in the soil.