A Mint State coin features no wear and very few marks or scratches. It certainly features no stains, unnatural toning or other discolorations. The manner in which the errors were formed is easy to understand. Rotated dies occur when one die is not mounted properly in the coining press and therefore a coin struck by that die will feature one side out of alignment. The degree of rotation varies from 5 to 180 percent.
History dictates that coins with greater rotations are worth more to collectors.
There is also no way of knowing exactly how many of each rotated die error exists there could be hundreds, there could be thousands. Although coins are periodically spot-checked by technicians for flaws, errors still occur. However, the number of error coins that escape the Mint vs. the total number of coins produced is very, very small a fraction of a percent. Not all coin dealers specialize in error coins. Most error coin dealers have a broad base of customers who collect error coins and are therefore more likely to know how to properly identify and value error coins.