Depends on the packet trick, obviously. One example is Sympathetic Aces, at the ends, everything can be examined, so if it CAN be examined, I always opt to let them. If they can't be examined but are still somewhat normal (As in, you can easily acquire matching non-gaffed cards) I don't use any type of switching device, I just have a matching set in the opposite pocket, put both hands in the pocket, after the effect has registered, then if they ask, come out with the non gaffed set. Pretty bold yes, but I use it for deck sw**ches all the time, with a bit of time management. E.g. Put deck in left pocket, grab coins, do an effect, return coins to pocket, come out with deck from right. They just naturally assume, especially with the time lapse, that it's the same deck you've been using already.

edit: What I meant by the beginning is, the more open you are with effects that can be examined, the more likely they will accept later effects as not involving anything fishy.

It depends on the routine, the act, what the gaffs are, etc. Personally, I close my stand up act with Dave Hoy's Tossed out Deck in an 'encore' format. I use a cold deck switching it for a normal deck used earlier in the show and have never had anyone ask to examine the deck. A better question is; "How does one go about 'ringing in' gaffs in the middle of a set of card effects?" I've recently created a set which I have been trying to put together for years and it took finding the right routine to with which to open the set. Ironically, the new effect uses 4 gaffs which are then used to transition to the second and then third effect.

Lots of good advice in this thread that I agree with. My rule of thumb is only hand the cards out if it greatly enhances the effect.

A good example of this idea in action is this street performance of Dia Monte by Diamond Jim Tyler. This routine has a great structure; it leads your audience to believe that one of the three cards must be tricky. The script is also carefully worded to make sure that spectators remember that all three cards were examined (and found to be normal) at the end of the routine. Remember, if you hand out stuff for examination and your audience doesn't remember this, then you might as well not hand the stuff out in the first place!

Marty

This has been something on my mind recently too.
Thanks for all the advice.

I love gaff effects, I use them as much as I can but only once in an effect, I mean if I do 5 effects 1 will include a gaff & never in the beginning you gain their trust by regular effects them hit them with a great gaff routine. They will never question your effect.

The Tool gimmick by David Stone looks great, but it merely switches focus from a gaffed card to a gaffed card box. Now instead of asking to see the cards, your inquisitor will ask to see the box.

I agree to the other advices given: deny, move on. Then again I don't like performances that leave people questioning the props.

Another solution: Just give all your gaff cards to ME! Then you'll never have a problem!

Great advice from everyone. I use gaffs, but sparingly. And I prefer subtle gaffs too. These are the kinds of gaffs that draw heat onto other things, rather than themselves.

But two practical ideas I've learned:

If you just did a gaffed packet trick, make it vanish at the end. Or change the cards into something else. In John Guastaferro's 'BrainStorm' series, he turns the packet into a rubber frog at the end of his opening trick.

Another idea I got from Paul Harris/David Blaine's 'Strange Travelers'. If they ask to see the cards at the end, you put them away as you say, "Trust me, you don't wanna know".

What great advice from all! I often respond by saying "Maybe later. Right now we've got this Magic Flow going..." Once in a while, even with a good, forward moving pace, an 'Alpha Heckler' will ask to examine something right in the middle of a routine. The important thing for me is to be prepared. Commit to memory whatever my choice of response is. Then put them in with the verbal 'outs' I've chosen to use when I make a (viewable) mistake. Then let them go until needed. I respond the same way when using gaffed and ungaffed items. I love the "I do offer lessons at reasonable rates" suggestion mentioned earlier. Might add that into my "mental response bag" for the individual who seems genuinely interested.