Roll Searching Marks Vs. Chop Marked Trade Dollars

It seems that some roll searchers (mostly Kennedy halves) mark the coins with sharpie markers, nail polish, paint, or whatever. I believe it has been posted that it is done so that they don't take time looking at the coin a second time. Or maybe it is to track if they get the same coins back. Since most of the coins go from the bank, to the searcher, back to the bank, rerolled at the bank or Brinks or N F String depot or wherever, and back to another searcher you would think that you would be getting many of the same coins over and over again.

Now in the days of way back Trade dollars were chop marked when they were good. Nowadays, it seems that the marks are used to indicate a coin that is unworthy.

So who has marked their coins and who has received one back and after how many marked coins? Also, what is the most unique marks you have found on a coin. So far, 2 marks is the most I have come across.