BTW, it looks like NGC does a security scan for all graded coins for free:
Link.
The weird thing about coins is that there is something called "dipping" in coins, which looks like it is basically putting the coin in something like an acid bath to remove the outer patina, and thus making the coin look "whiter." And this is somewhat accepted in coin collecting community, and the major TPG's like PCGS and NGC still grade these types of coins with a number grade, and do not give them the "CLEANED" qualifier that it does to other coins that are cleaned in a different way. (This is like an extreme form of soaking for cards, I guess, but most anyone in the card community would say that if you used chemicals to soak a card, that is card doctoring.) Anyway, supposedly CAC, which is a coin grading company founded by one of the original founders of NGC, who later left, will only put their sticker of approval on coins that have not been dipped.