Determination of Cleaned by grading companies

WhiteTornado

Perhaps OT a bit, but please bear with me. I find I get better and more civilized answers here than the Liteside.

A couple of days ago, I got back my first ever submission of anything to any service. Turns out my 1913 Indian Head Quarter Eagle (U.S.) was graded "Net EF-45, Cleaned" by ANACS.

My question is, how do grading services determined if a coin has been cleaned? If you have a coin that's well worn but also "bright and shiny", that's a dead giveaway. But this one was much more subtle.

I'm certainly not challenging the Cleaned status. I trust ANACS got it right. But rather, I'm wanting to know for my own benefit, so I can avoid unknowingly picking up such coins in the future.

291fifth

ANACS is very tough on cleaned coins because they net grade. Even if a copper coin is fully retoned they will still give it a cleaned designation, though in this case they usually don't deduct much from the grade when assigning a net grade. When you see as many coins as the graders do you can spot the subtle differences in cleaned coins. My understanding is that ANACS doesn't have much of a turnover rate among its graders so they become very skillful at detecting various types of cleaning.

WhiteTornado

Sounds like the skill of detecting cleaned coins comes mostly from experience, then. Thanks for the input, 291fifth.