Considering the high premiums paid for coins bearing CAC stickers, and the low cost of making the stickers, the temptation surely has already prompted someone to falsify the CAC endorsement. Has anyone seen or heard of any counterfeit CAC stickers yet? Other than identifying the housed coin as being average or substandard, how would one be able to tell?
CAC has a publicly accessible cert database where you simply type in the cert number and it tells you if the coin has a gold or green CAC sticker or if it has no sticker.
Assuming everyone checks this database, and the coin show you are in has decent data connections. I haven't seen it myself, but I have seen certain dealers using more green oval stickers on their slabs, the ones saying "great" or "good deal" etc. I am sure the color choice is just a coincidence.....
I was at a show where a dealer had a coin in an old PCGS holder he tried to upgrade with the cac sticker on it, when he sold me the coin he gave me the cracked out holder and said that if the coin came back in the same grade when I submitted it, he could get the CAC sticker on the newly certified coin assuming it did not upgrade. There's probably too much risk to reputation with cac sticker faking, it would be a one trick pony and then the gig would be over.
I can remember when there had never been a faked slab, and it wasn't very long ago. But then they showed up and today they are rather common. So if there hasn't been a faked CAC sticker, there probably will be before too long.
I don't think someone who would fake CAC stickers would care much about reputation. I doubt it would be a dealer in the first place. But anyway, let's all remember that not everyone in this world is a crook!