Red Dime ? What's The Meaning Of This

Such establishments would often paint coins as "house money". It was usually red, but no doubt there were variations. The idea was that the establishment could put house money into the juke box (or give house money to a favored patron to use) and could then determine how much actual profit there was from the vending machines. There were other uses as well, such as detecting pilfering of the coin box at a remote location.