Or any other card trick that involves you finding their card. If it is wrong, you can ask them what it is, secretly cut it to the second card from top of the deck, then execute the snap change.

or say that wrong card used to be theirs you just magically changed it

To quote from B_Magic's suggestion: Just go for the invisible deck. You get a great trick, and if you screw up and easy way to "come back" i.e..."this isn't the card you picked? Weird? What was it? Are you sure??? You didn't see me go into my pocket, or use anything but these cards here, did you? Well that's strange because in my other pocket I have another deck of cards, and look...one card is turned upside down..."

yeah, an invisible deck might be good for that type of situation.

dont carry aound multiple decks, too much baggage, it also makes you look phony with decks everywhere... just throughly practice ways to overcome your faults, an ambitious card routine is a quicks and easy way to astonish with out too much preparation, if I get screwed up or are at fault, I will just do some type of flourish... youd be amazed how people react to a outlandish cut or a nice fan.

wierd i always carrie 3 decks svengali, stripper and a plain deck . plain was for them to inspect hehe oh and IT