This is a very powerful trick. Regarding of being caught, set aside the magician thinking. For the spectators, especially if your approach is friendly, you don't need to prove to them anything. First their card is there then poof, it's not there anymore. That alone can make the specs gasp in amazement. To them, it's amazing, no doubts or anything...unless you really have a F#*&(#& spec there.
That is why Jay said that never mind the rest of the cards, all their attention is with the magic. 
