Cleaned or improperly cleaned? For improperly cleaned - impaired luster, hairlines & unnatural wear in high points, lack of toning or toning remaining only in some areas.
any cleaning effects the value of the coin unless you are dealing with ancients. You have to properly clean ancients to preserve them. This is not neccesary with modern us coins though.
Agreed, the cartwheel luster, or lack thereof, is the first thing to look at. A cleaning will generally leave hairlines and other artifacts like others mentioned. However, over-dipping will not. Dipping eats away at the top layer (luster). So if the coin had a carbon spot or other dirt issues, the dipping will remove the spots along with the luster. This leaves you with areas where the luster breaks.
Here's a great example of a cleaned coin. It belongs to someone here on CT but I forget who. You can see the surfaces and how they have been damaged. I have included another pic of a coin that has not been cleaned so hopefully you can see the difference. Dang, I messed up by not clicking full image for the panda coin, hopefully you can still see the difference.
Know I am being picky, but you have high aspirations and should know that harsh "cleaning affects the value" of coins - only if you can detect the cleaning. The effects of cleaning show up in fine hairlines mostly visible on flat fields, but also on the figures in the coins. Cleaning methods that do not involve rubbing of the coin (dipping) are generally undetectable until the diping process has disrupted the surface enough to cause lack of luster. Since not all uncirculated coins have luster, any disruption of surface finish should raise red flags about harsh cleaning.
The coinage metals are usually considered to be gold, silver and copper. They all do have different surface chemistries, but harsh cleaning would show up in similar ways on all of the three.
I think it would be helpful if we just started posting some photos of cleaned uncirculated silver coins for mrgooch.
Look at the circular swirl lines on the neck and face. Also, the coin is absolutely lifeless, and has a dull finish, indicating lack of luster, in a coin that would have had good surfaces--it would have been solidly uncirculated, but it was wiped, polished or buffed (the circular hairlines are a dead giveaway).
But do you have any that bad ? And no, I'm not trying to be a wise guy. You see, to many a problem free VF is much preferable to a problem unc details.