and maintainer of:
I was riding the bus to work today and I saw a small poster from the bus company informing the passengers that falsified tickets are in circulation. Apparently there was also a flyer in the topic, so to shorten my bus ride I grabbed one and started reading.
The flyer gives very detailed information on how to identify the false tickets - actually the information is so detailed it would be a dream to receive as the maintainer of the falsified tickets.
The flyer (in PDF) is in colour and give precise information on what bugs to fix in the current batch of the falsified tickets so they will resemble the original tickets almost completely.
Serial numbers would of couse still be the problem, but since humans cannot decipher these anyway, they would not be caught by the manual control checks and therefor would pass as valid.
It is one of the better bug reports I have seen