TBH if you perform it in such a way, there will be no reason for the audience to want to inspect anything. When I need to ditch something I usually just casually put my hands in my pockets while I talk. It is a natural thing anyway and if you do it throughout your performance it becomes conditioned in the audience mind. I do not know how decoy works, but I assume if you are performing it, you could make the fact that you are using it an afterthought and point the focus somewhere else.
Let us use a "Svengali Deck" as an example. People never ask to "see the deck" because I end on such a high impossible note that the deck is almost an afterthought. For example the last phase is typically me showing that their card has vanished from the deck and reappeared somewhere impossible (girls purse, my shoe, the card case, etc.) so when I "vanish" the card, I put the deck in my pocket and show that both hands are empty. At this point the focus is not on the cards anymore but on the fact that my hands are empty and there is no way I could sneak a card to that location. They leave wondering "how did it get into my purse?" rather than "I wonder if he was using a trick deck?" because a trick deck would be irrelevant to how the card got into her purse. Make sense?
