There was a story of an east coast hunter, who ....... after many years of hunting .... had gotten a fair handful of large cents in his collections. One day he went through the coin book, and decided that a few of them, based on the date, and the details he could make out "should be worth some money". So he decided he would take them in to coin-collector store, and see what they'd offer him. He puts 6 or 7 of his better date/condition large cents on the counter. The dealer looks at each one with his loop, and studiously studies the coin book guide to compare. And one by one, he offers the guy a mere pittance! When the md'r objected and tried to point out the details on the coins, the fact of the better dates, etc...., the dealer laughed and said:
"But your coins are all dirty and cruddy. Thus there's no way we'd offer you those book prices".
When the md'r heard the dealer give that reason, he replied: "
Oh, so if I clean them up, THEN you guys can offer me more money?" When the coin dealer heard that, he BRISTLED with disdain, and said:
"NEVER NEVER clean coins. If you did that, then for SURE we'd offer you even less, and would not even want them. It's a no-no to ever 'clean coins' "
So the md'r, dejected and sad, gathered up his coins and left the store
Once home, he figured that as long as they're not worth much, he might as well clean them for *just* his own home display trays. He studied all the various ways and methods of cleaning old copper coins. He experimented with various methods on worthless IH's and the common worn large cents he had. Finally, after much practice and study, he settled on the method that left the least trace of any presence, yet lifted dirt, and revealed detail, without evidence of effort. I forget which method it was.
A year or so later, when he was all done, and he had his coins in his trays, he decided he'd try again to see if the coins had any value. He took the SAME 6 or 7 coins over to the SAME dealer's store. When he entered, he could see it was the same counter clerk who had waited on him a year earlier. The clerk apparently didn't recognize the man, yet the md'r could recall that this was the same clerk. The md'r did not remind the clerk of their earlier meeting, and instead, just put the same coins (now cleaned) on the counter. And again, the clerk pulls out his loop, and compares each one to the book guides. THIS TIME, one-by-one, the clerk offered much better offers than the previous time.
So you see, the old addage of "never clean your coins" isn't necessarily true. The old addage was probably born out of horror stories of someone "cleaning grandmas gold coins with ajax", etc.... But as you can see, if done right, it can actually add value, to some of the stuff we md'rs find, that admittedly isn't worth much in the condition we find them in (caked and colored, etc...)