What Is A Cleaned Coin?

A cleaned coin is one where it's original surfaces have been disrupted, altered or impaired by rubbing.
It's impact on collectibility and slabbing? Simple, it's a problem coin now.

a cleaned coin is one thats been put in the washing machine with your pants by accident. Nah all jokes aside a cleaned coin can come in many forms from being dipped in something like EZest to whizzing where you use a rotary took and wire brush to try and create false looking cartwheel effect and everything in between. The most common is probably caused by someone taking a rag and wiping the coin trying to make it look better when they don't know they are ruining the coin. The particles that the rag holds from dust to dirt scratches the coins surface which puts directional lines on the coin

A coin that has been held to a wire wheel until it shines is usually considered cleaned. Ccins placed in battery acid for several days too should be considered cleaned if anything is left.
Actually if you look at the top of the page you would see a tab for Search. If you tried that and typed in cleaning coins, coin cleaning, Acetone, etc. you would or should find a zillion posts about this subject.
For many reasons people just like coins to look like they did when first made regardless of how long they've been in dirt, dust, grease, tar or all the other things that happen to coinage.
And when it comes to substances used to clean coins it is an endless list. I would suspect one of the most common substances used is SPIT. So many people just spit on a coin then rub it to see how it should look, could look, might look. Which is why you should never put a coin in your mouth.