I would have two decks set-up and if they shuffle th eone just do a deck switch.

well if they want to shuffle the deck means you didn't convince them to trust you. Make them trust you so they are at your disposal ... sorry for spelling mistakes if i have any :X

I never have run across anybody wanting to shuffle my deck because i usually don't do set-up effects unless they are killer like a cool triupm routine Called "Slyumph" in which i just switch the pack.

especailly the last one is great man, really

Hahaha... This is 1 of the best ... very convincing ..

i would have done it like that to but if you can then let em put it into the middel of the pack and then contol it to the top talk a bit while palming let em shufle place card back on...
people who want to find out the secrets in a "pick a card trick will always lock very intens at there card so if you are placing it at the top they will have focus at the top card that you are palming wich gives a bigger change that they will see you palming... (if you are getting catched with a card palmed you are very stuck...
so do the card control if you can
sorry for my spelling im from denmark... hope that you were understanding what i meaned...

say "last time i let the audience shuffle..." start doing a renegade shuffle only without reversing a card "...bad experience" then 'fix' the deck then continue on

Well.. thats what magicians are for... patter alittle gives a little misdirection and fast in putting your hand back into the deck so that you could place the chosen card back to the deck. Anyway bigger movements covers smaller movement or the body movements cover your hand movements. You could try this...

if he asks to shuffle the deck, then tell him to pick a girl from the audiance to shuffle the deck. when she's up on stage, tell them both to go to the bathroom for the girl to shuffle his deck/package

when i'm at a table, and someone asks me to shuffle the deck, i go (while lapping it): what deck?! (my hands r still apear to cover the deck, but their really empty)
the spectator: "the deck ur'e holding..." i show my hands empty, and produce it again from my pocket. (they'll forget the ever asked u to shuffle the deck, trust me)

Tomer

Sometimes I start with a stacked deck, so when I bring it out I'll false shuffle and cut.
I have a short routine with the stack, and the last part of it destroys the set-up.
Then I let them shuffle all they want, and go on to regular tricks.

If they insist on shuffling, I'll let them and just cut the stacked routine out.

Although Mike Close credits Ed Marlo's imperfection force from 1947 in his review of Stealing Pips, I have found the "dirty deck principle" in Greater Magic (p. 82), a book published in 1938! The creator is alluded to: "One of the most adroit card men in magic has employed this principle for years." This also implies that it was old news in 1938.

Back to your regular programming.

I wouldn't let them shuffle. You mey get people that don't handle cards that often and they'll fumble the deck and possibly drop it and next thing you know you're both playing 52 pickup and the thunder's gone from your trick.

Just say, "Shuffle?? I'll do one better I'l let you cut it wherever you'd like!!" Then just do one of the various force cuts out there. There's one called "cut deeper" which is quite convincing. I belive it's by Daryl.

put a bend in the corner of the card and let them shuffle and you know what there card is, EASY

I used to get people who would chant: "Trick shuffle trick shuffle" even when I wasn't performing one.

However, when you have a stacked deck that obviously cannot be shuffled, you'd be best off not letting them touch it. I always say that this is a new deck and that the oil on their fingers ruins the finish. If they still insist, get them to pay for the privilege, perform an impromptu trick, and let them keep the deck, as it is ruined. Then go on. If it's a gimmicked deck, use one of the lines above. You obviously don't want to give that away.

If they ask to shuffle it in the middle of a trick, tell them, "Let me just finish this, and then I'll explain why I don't let people shuffle the deck."

Then follow up with a Triumph routine, showing that the last time people shuffled the deck, they really screwed up the order of things.