Uncleaned coins are a
cheap way to start when you have just developed an interest in classical
numismatics. They slow the
new collector down so they don't blow all their
money on mistakes before they know what they are doing! The actual cleaning process can be fun for most people.
Attribution of uncleaned coins is fun and a great learning experience. If you buy uncleaned coins, you should buy them for the experience itself, not just the final results.
Uncleaned coins are not the way to build a nice
collection of coins. Even most of the attributable coins will be lower grade. Most of the nicer coins will be the most common
types. These days most coins are cleaned by the finders or the wholesalers. They look at the coins and decide which ones to clean and which ones not to clean. They base their decision on maximizing profit. So, uncleaned coins are coins they believe they can sell for more
money or faster
money uncleaned than cleaned. If they have a lot of nicer coins and not enough time to clean them, we uncleaned sellers and buyers might get lucky. If the finds are slow, they probably clean everything but the worst junk.
We like to say the coins you get will be worth about what you paid. So if you buy 10 uncleaned for $3 each and get 3 coins worth $10 each retail and seven slugs, you have received coins worth what you paid. That assumes you don't destroy them with your cleaning efforts or that you were not unlucky. Also, keep in mind most $10 retail coins are not so great. Of course every once in a while you might get a
rare AE 4 or something worth more.
Buy uncleaned for the experience, not the result.