Or in this case who knows HOW many posts on a message board to get one with some thought behind it. This is cross posted from another forum where an essay calling out the importance of signing cards and ending clean in magical effects and my response.
Over the summer I performed magic as a pirate for the local six flags. I could not have the cards signed as markers and pens would have been EXTREMELY out of character. I still did the same magic I normally do (Card on floor, dollar transpo, etc) without the usual signatures. They got the same responses as normal.
People don't think in the same lines we do. They trust us (And those who don't have a reason not to). If your conviction is strong enuff, seldom will they question you. I have been doing card to wallet for I dunno how long now (Unsigned version). Showing it no longer in the deck and then in the wallet is enuff proof for them. I have a signed version I can do as well if necessary, but it hasn't presented itself thus far.
Michael Close had an essay in his workers series about how people don't take into account the amount of prep we as magicians are willing to put into something. They don't think we'd have three outs to a trick in our wallets (Thank you David Regal), they don't even KNOW double backed cards exist, and if you have a confederate with a duplicate card somewhere ready to go, well then forget about it.
I will admit, there are some effects I would NEVER do without a signature... however it adds to the performance. It's not just there for the sake of it's own magnificence.
People believe us because we tell them to. This is why magic works the way it does and also why people like the Asshat and Criss Fishing Rod are on TV still.
On ending clean, I have learned that, sometimes, it's just not necessary. We have a habit of trying to get our hands empty ASAP if we hold out at the end. A good example of this is Perkins' In Your Face Change. I have been doing it for people and it has such a STRONG slap in the face impact, that they can't reconstruct backwards cuz' their brain shut down on them. If your magic can be that strong (Not confusing. "Confusion isn't magic" - Dai Vernon) then you can hold out as long as you want and clean up later down the road.
It's all relative... so ask yer relatives this Holiday season.