My most recent challenge: why is it good to clean coins but not good to clean coins? I struggle with overdoing research, so I've seen dozens of answers. I have some coins I don't know what to do with because I think they may be worth a few cents more than face value, but they're so grimy and filthy I have to do something. Is it at least appropriate to "clean" a coin by only releasing all that dirt back into the wild? If so, how? I do know that anything abrasive, acidic, and most chemicals are no-nos but I don't see coin photos anywhere that don't look at least a little dressed up. There really shouldn't be a double standard related to whether I want to keep a coin or try to sell it. I watch supposedly respectable dealers online who say it's OK to clean coins but only on alternating Tuesdays that begin with a T and if the moon is in a certain phase plus you have to taste it first so you'll know what you need to use. Last part of the question is this: with so much at stake grading coins, valuable or otherwise, are the grading services as consistent as you would hope? Do the guys grading have bad days or slightly differing opinions on the ultimate results? What happens with extremely valuable coins probably won't ever affect me, but I feel badly when I read about someone who lost a huge percent of value by cleaning/not cleaning appropriately then getting a much lower grade than they needed as much as they wanted. As always, I appreciate everyone willing to tolerate my ignorance.