There is a popular misconception related to cleaning coins.
First, coins that have a dark, thin uniform patina shold never be cleaned. That goes for copper, nickel, silver or gold coins. This "look" identifies them as original coins, and they do command a premium.
Coins that are off-color or mildly spotted may benefit from a chemical dip (no abrasion) cleaning, but I'd refrain from that on key-date coins, line 1909-sVDB Lincoln Cents or 1916-d dimes. But that 1817 Large Cent, 1882 Indian Cent, or 1857 dime will see no harm.
Coins having heavy corrosion or generally black surfaces will not be harmed by a cleaning, and nearly any cleaning is acceptable as long as it does not create heavy scratches (no wire wheel!). These are the types of coins generally retreived from the ground and most characteristic of long-buried copper and nickel coins. Remember, too, silver coins having one small spot will be considered "corroded" and will be labeled as such by one of the three major coin grading companies (PCGS, NGC, ANACS). PCGS labels them as "Environmental Damage" while ANACS calls them "corroded" or "heavily corroded".