When a bill has a little bit of ink on it?

Question

Does that mean it was in a bag that had an ink bomb go off in during a robbery?

I see bills that have a bit of pink or blue ink on the corner all the time.

Answer 1

The new printers and copy machines could copy the old bills too well there were too many forgeries out there.

So they came out with pens that react with the bills and will detect the wrong the kind of paper. They look like felt pens. If it is a mark that looks like a felt pen mark it is from somebody checking if the bill is real or not. I see a few of them.

With the newer bills that don't copy and have watermarks in them they are doing this less.

Answer 2

We used to mark the money in the ATM so we didn't have to remove it all to count it when balancing it.  We would do this by using a marker and marking around the edges of the bundles of bills.  More than likely, that is what you are seeing.