Cleaned Coins

This is certainly true and one of the harder things to tell. A cleaned coin generally has a look of too clean, and light hairlines scratches on it. An over dipped coin (using a tarnish removal solution) will have a minuscule amount metal stripped away and this leaves the coin quite dull. The best way to tell a cleaned uncirculated coin is to rotate it slightly while viewing under a high intensity lamp or light source, a natural uncleaned coin will have a cartwheel like effect of light a cleaned coin will show breaks in the cartwheel of light. Other methods of cleaning are more obvious such as polishing which produces a too bright coin, and usually the coin will show signs of obvious wear from the polishing tool. Some cleaned coins are very misleading, and years of experience is required to tell them from uncleaned coins. There is no one way to tell, but as most of us that have been in the hobby or coin business for more than a decade or so will tell you it just doesn't look right, that comes form seeing 100's or 1000's of examples over the years.

One method of learning more about cleaned coins is to use the Search tab at the top and type in cleaning coins, coin cleaning, or cleaned coins.
One of the most common methods is if the coin has a lot of wear and there is no dirt inside the letters or numbers, most likely cleaned. By that I mean inside letters like an e or o or numbers like 9 or 8. With relatively new coins, only a few years old, that becomes a problem since they usually don't accumulate dirt that fast. Many dealers will take a high graded coin, very little wear, and clean it since that makes the selling price better. Coins of very little wear are really difficult to spot claning.

Dirt maybe. Worms should never be messed with. They borrow through the ground airating it so our plants can grow better. AND if you replace that coin, with the dirt and worms intack, you may well get a coin tree someday.
In reality, just remember that you can do whatever you want with whatever you own. If you never, ever plan on selling a coin, you can wash it, drill holes in it, bend it, melt it and/or even plant it for a possible, someday coin tree.
IF, however, you think someday you'll sell it, give to another collector, leave it to someone that cares, if and when, best leave well enough alone.
For a coin found in the dirt, a rinse with distilled water and/or Acetone should do whatever is needed.

Thanks for the photo @CaptainFwiffo!
Can anyone post a photo or video showing this "cartwheel effect" on uncleaned coins vs. "breaks in the cartwheel of light" in cleaned coins?
Photos & video show so much more information than words.


Another post asking how to identify cleaned coins...
https://goccf.com/t/116270

Ancient coins are an excellent example. Most of them will come out of the ground with a layer of dirt, gunk, and crust so for the sake of at least identifying them cleaning is a must. And the value will actually rise when the end result of the cleaning is a nice and detailed ancient coin (though not always depending on their condition).