Yes...the luster is destroyed by polishing a coin. While Luster causes a coin to shine, shine and luster are two separate things. As quickly and simply as I can explain: Luster is created by the metal flow that happens when the die presses into the planchet. When the process is complete the fine microscopic top layer of the coin looks like this ^^^^^^^^^^ These raised areas flow from the center of the coin out to the edges in a radial pattern. This is what causes cartwheel luster. when you polish a coin it knocks down that lusterdown to something like this mmmmmm or even something like this _________ This will cause the cartwheel affect to disappear and you end up with a coin that is really shiny but has no luster. Once you get good at detecting luster, a polished coin will stick out like a soar thumb.
Another reason not to clean and polish coins: You don't want to prove beyond a shadow of a doubt that you are dumber than a doorknob, which you are if you clean and polish coins.