I regularly perform Louis Falanga's
"Virginia City Shuffle" which is a packet trick that can be examined at the end if need be. After some other card effects, and in the right setting, I bring it up by saying "Sometimes people think I use trick cards. Well, I don't. Usually. But I do have some here in this special wallet. Would like to see them?" Then I present the effect as a story about a time in which I went to a magic shop and the magician there was trying to sell me these special cards. It works great for a couple of reasons. First, cards can be examined at the end and are technically not "gaffed cards" anyway. Second, there are usually no other suspicions later when using my regular deck. Later during another trick, the spectator's mind is saying,"Well, that ws amazing! And he's not using trick cards, because he showed us the trick cards earlier." It also promotes an attitude of honesty and genuineness. They think you are sharing a special secret with them.
The old "it must be trick cards" solution is probably used as often as the "it goes up his sleeve" solution. By emphasizing it during one effect, it subtely discounts the trick card theory with a regular deck later.
I am not sure who said it, but I heard that if you are doing sleight of hand and they think the cards are gaffed, you are doing your job. And If you are using gaffs but they give you credit for doing great sleight of hand you are also doing you job.
This certainly depends on your character, presentation, and goal in performing.