I had a strange box of half dollars to go through yesterday. I have been getting at least 4 boxes per week from the same bank, and am familiar with the way 6 or so prolific coin markers write on their coins.
This box held dumps from a different tagger. He puts a red slash on every '74 D, and I found 30 of his rejects in one box. The strange part is this same box also held my first ever '74D double die!
It just reinforces my belief that the coin supply is bigger than any individual can influence.
BTW, the marks on most coins are wearing off due to circulation. The scarcity of silver seems to be causing them to give up.