Everybody is always saying never to clean your coins and I wonder does that go for polishing your coins??
There are ways to properly clean coins, but you probably shouldn't clean coins that are more expensive. Even if you are properly cleaning them. Polished coins can look cool, but don't do it to an expensive coin because then the coin will only be worth a fraction of what it used to be worth if polished.
Cleaning and polishing a coin both equate to damage. Polishing wears off high points and details of a coin, decreasing it's value by a great deal. Cleaning a coin can also lead a coin to lose most of it's original detail.
Anything that removes the surface of a coin is cleaning, and that IMO is what polishing does. It is currently a given that you should never touch or do anything to the surface of a collectable coin as it will devalue it.