Agreed. I wouldn't wipe or rub a coin. A soak in acetone, a dip, a rinse with acetone, water, or ammonia; these are generally ok. Not a wipe or rub, though.
Pictures would be a big help. If there's a haze that acetone won't remove, sometimes sudsy ammonia will help. But without seeing the coin i don't know if it's a candidate for that.
acceptable cleaning is when the TPG does it. Nothing more, nothing less. I'm really just joking, but it's market acceptable (maybe)
That is true. "Cleaning" is in the eyes of the beholder, including the experts. The say thing goes for toning. A piece can be dipped, but if it comes back with rainbow colors, some people go ga-ga over it. if you showed them the same coin, just after it was done, they would reject it because "It's not original." A dealer Boston came up the the term "original now" for dipped coins which retoned.
To get a better idea of what rubbing a coin with cloth will do, try this. Take a proof cent that has problems and is almost worthless. Study the surfaces first and wipe the coin with any type of cloth. The mirror surfaces will really make the hair lines stand out.
As a normal I don't believe they can. I have gave hundreds of coins an acetone bath and sent them in for grading. Never had a problem. There is one thing to keep in mind. The surfaces under whatever the acetone removes may be really ugly. The coin may have looked better before the bath.
Usually acetone just melts away gunk, rinses dirt, lifts fingerprints, etc. The solution evaporates so quickly I don't think it even leaves a residue, unlike water can.
Honestly I don't know how they even grade them. It's witchcraft I say. The imperfections stand out like crazy. I think they just flip a coin when it comes to a straight grade vs details.
