I find I am never unprepared to perform something...
I walk around town with at least 3 decks of cards. One is pre-set for red Hot Mama, and the other for Spec cuts to the aces. My third is a Bicycle all plastic See through Deck I got because they are great for practice.
After either Red Hot mama or spec cuts to the aces, i do Twisting the aces, Dr. Daley's Last Trick... Both from Ammar's Card Miracles Vol 2. I will also do " That's it". This is a " Pick a card" trick with an interesting premise You tell them that you are getting a lot better at spotting liars and want to see if they can fool you... They select a card, which is lost in the deck. Then no matter what you show them they are supposed to say.." That's it" to try and fool you... You show 3 cards, one of which IS their card...but when they say that's it... you say.." good try, but no, that's not it." then you show the card you THINK is their selection... when you look all confused when you realize that it's not, you ask " what was your card?" They'ss say, and you reveal that the card you are holding IS their selected card.
After that depending on mood, I may finish with Jazz aces. Which leaves them totally stumped.
I have been practicing Fiber Optics, and will be carrying around a piece of rope with me once I have it perfected.
Personally I agree that we should be prepared to perform at the drop of the hat. I think it adds to our mystique that we are true magicians.
" I am not prepared." should never be our response.
" I don't have anything with me." is most unprofessional, since it implies you are a "gadget and gaff magician" and while I think Gadgets and gaffs have their place, they should not be the backbone of our art. It also tells them that it's not you performing magic, but your props.
" I am not in the mood." ...Ok, sometimes we are just not in the mood to perform, I know how that can be...but for those occasions don't do a LOT...Just maybe 4 or 5 minutes worth of something... after all, you never know when someone will know someone with a party coming up... etc...
And if you just don't have anything to show them because you are unprepared, don't say that just do say.." I am not in the mood..." or .." My hand is cramping up something fierce." Or.. "I have a headache." Many use that to get out of performing... and not just magic.
It's funny but I just finished watching a show where Teller was talking..( Yes, he actually talks) about sleight of hand. And he said.." the amazing thing about sleight of hand is, that this way, you can if you had to... perform...naked...on a beach... and I have performed... naked...on a beach."
I think that says it all.