You can fool people like Sheldon from the big bang theory by cheating together, but normal people like Penny would definitely figure out the way you operate the playing cards. However, you don’t have to be Sheldon for he wanna buy uranium from craigslist, but there are already three common ways to read cards from their back. Every poker player knows the fact better than others, which is if you can recognize playing cards even without looking the front, then you have a big chance to get a jackpot in poker. That being said, either you are a reliable guy or a card shark, you should learn those methods anyway, to protect yourself or to cheat, it is up to you, I am the one who carry with knowledge and messages.
The first method comes to my mind belong to cards with passwords, what I mean by passwords is those cards are produced to be slightly different from each other. If you are a reckless person you would only see nothing but the same back colors and graphic pattern of the whole deck, you are not aware of you are playing with a secret pack and ready to get screwed by the host of the deck. The passwords are tints and black-outs, every these deck would be wrapped with a detailed instruction about what the codes stand for, and every manufacturer company has different print solution. For example, a very little black dot in a tiny area of the back of a play card may refer to Ace, and two may refer to King or two. This is an easy solution only with little memory.
The second method is luminous marked cards, this one is not easy produced and highly needed advanced technology and skilled handwork. Those marked cards must assort with other cheating devices like spy sunglasses and contacts to read or filter lights. They often marked by special invisible inks and portions which only can be detected by the above spy devices, and those tools may work together with scanners and readers to predict future cards, that is even better and high technology, so price is not cheap for normal cheaters. Luminous marked cards have a variation, video-luminous marked cards, this system is used for many purposes not only cheat in poker, like it can monitor the game to see who are playing scams, and also to analyze the math behind the game, etc. It transmit the signals to screens or computers in another place from where players are.
The last one is not exactly a tool or a random object, it is a skill which not many people would learn through. There is a single word for this skill, observation, that is it. You see, even the most awesome DNA would make mistakes during copy itself, not to mention the production of playing cards. So the fact is cards in one deck have unperceived and latent print diversity, not all of them, but few of them would change the game results in a splendid way. The texture, figure, inks, lines would all possibly appear to differ from the established pattern, and by that, a poker pro would easily and unwittingly recognize most cards of a new deck after play it like three or four times.
So in conclusion, the easiest way to apply those three methods, I think they should be the first one and second one, as passwords and marks. But if you invest your efforts into the third solution, and finally master it, then you will be rich in a safe way.