Never play cards with someone wearing sunglasses
While wandering around the Internet (as you do) I found [cardsorcerer.com->http://www.cardsorcerer.com], an interesting site about marked cards.
Most of my knowledge of card marking techniques came from books such as ‘Scarne on Poker’ and although the basic methods remain the same, it’s interesting to see the modern versions of these techniques.
I don’t use marked cards in my magic - it’s just not needed in the sleight-based card tricks I perform and not practical when you go through as many packs of cards I do. Marked decks and marking kits are pretty expensive (there is one system on this site for $900) and if you mark cards yourself, it’s too time consuming.
However, I can see why marked decks might be popular right now. A lot of people are performing mind reading and mentalism effects and marked cards lend themselves to this style of magic.
Also, poker and in particular Texas Hold ‘em, is a popular game at the moment and there are plenty of people who will cheat to win. Poker variants like Texas Hold ‘em which have community cards are particularly susceptible to cheating with marked cards. The backs of the community cards are in full view on the table and there is plenty of time to spot long-range markings such as tintwork or juice.
Of course, [cardsorcerer.com->http://www.cardsorcerer.com] has a disclaimer saying that the cards supplied are for entertainment purposes only. I hope people who want to cheat read that.
The lesson is, never play cards with someone who is wearing sunglasses.