Spoiler for unsuspected
Some poker cards would look different if turned 180. There are 22 of such (e.g. Ace of heart,of spade ,of clubs)
It is hard to remember all their polarities from random but only about half of them should be pointing north..thus the others pointing south.
If by chance one of these was picked and the deck polarity is always maintained during the riffle shuffes,
then it would be up to the chance of turned picked card when returned that finding it is possible.
This is increased when the deck is spread from right to left.Not sure but observed.
When awkward, the picker should be using the other hand on the card causing it to rotate.Witnesses passing around for checking
can also cause that card to rotate. Anyway,when a card is extracted from the rest it may returned with different polarity.
So, it is 1/52 X(A)X(T)
A =the number of memorized asymmetric cards polarity
T =chance of a turned picked card when returned to deck
Polarize all asymmetric cards to one direction before hand..so no need to expose the cards.
Polarity of deck shall be kept during shuffles.
When the picked card was drawn and shown you are opt to rotate or retain the deck on hand in
order for the picked card to be returned to deck on counter polarity as much as possible.
That then would be 22/52 chance.Favors a 1 bet that pays 2.
If you failed to find it, then the picked card is a symmetric one..with 1/30 chance guess.