Some people who search coins suffer from a mental problem where they actually believe that once they search a coin roll and mark the coins that this somehow takes them out of circulation and that no one will ever see them again and that no one will ever make more deposits and that you wont find silver in the marked coins ever...
Fact is, its a way of thinking that is very very very limited in its scope.
Fact is also coins are going in and out of the system all the time. What happens when coin collectors kid takes em not knowing, or wife, or what happens when someones wife sends them to the bank due to divorce or because she maybe caught him with another woman...who knows, maybe someones kid inherited coins and needed cash to buy drugs. And of course just ignorance due to a couple generations not knowing there are "real" silver coins out there. How many tellers do we know that will save and give us the silver at face when they work at banks. They dont know they are worth more they just think we are cute or crazy.
Because of these factors you find silver with marked coins all the time. A couple weeks ago I found some 40 BU ben franklin coins all 62s and 63s, they were like new, and in along side them where coins marked with red and black and green and all sorts of colors and marks.
Fact is, those marks did not protect that box or those coins from coming into contact with more silver.
EVEN Stranger is that 40% halves that I have found marked...And the occasional full roll of 40s or 90s that you find in someones dumps...is it that? or did someone just take in a roll and never checked or knew to a bank where someone else dumped...either way, Halves are gonna move.
Marking only proves one thing. that no matter what, the coins circulate and move around.
the only coins I have marked are tokens that I found in fed rolls as I know they will go back to them. and some of those marked tokens have come back to be in fed boxes at banks I dumped at and Golly gee there is silver mixed in.
If you find some weird angle coin with 3 holes drilled in the rim, thats me. I dont mark the normal halves as its pointless.
I also make it a point to spend halves localy. When some business deposits them in a change machine it may be just a few dollars off from being send in to be re rolled. And some of those bags are years old!.