I get various marked coins all the time, but never in a large quantity. Some CRHers will mark their dumps so they know if they get their own rejects back. Usually when the coin rolling companies box them up, they get mixed with all of the other coins, so you can sometimes find marked coins and silver at the same time.
Zas, marked coins do not indicate the box will be a skunk. People have searched coins for years and like dogs,they can't resist the urge to mark their territory. I have found keepers that are marked. Since I don't search for dates(just silver), I just edge search and back up my search with the "bounce test". I have probably thrown back hundreds of errors,proofs,etc by my method. I don't have the desire to collect but those that do still find gems in my rejects. Cheers, Jim