The question of magic secrets here on the SDMB seems plagued with a type of ‘Sorceror’s Apprentice’ problem (rather appropriately). The more one attempts to clear up misunderstandings, the more they multiply - leaving us all back at square one and none the wiser.
The point that Peter Morris has tried to make above, and that I’ve tried to offer in past threads, is that asking questions about how magic tricks are done is to a certain extent futile, for a simple reason: the people who are in a position to provide accurate information are generally disinclined to do so. In other words, magicians tend not to discuss how magic tricks are done on free (or free-ish) pubic forums such as this one.
Within the magic trade, the general ethical view on revealing or discussing secrets is this: serious interest is welcome and encouraged, casual curiosity is unwelcome and discouraged.
Expanding on this: if a person has a genuine interest in magic as a performing art, and if they are prepared to go to some time and trouble to discover how a trick is done and how to perform it… well, that’s okay. There’s nothing wrong with them buying the relevant book or DVD; or paying for some personal tuition; or joining their local magic club where they can discuss method and technique with others who share the interest. All of these are good ways in which magic is passed from one generation to the next. What we (in the trade) tend to frown on is simply giving away the secrets via public media (such as this) so that anyone with even the most casual passing curiosity can learn the basics of how such-and-such a trick is done. Rightly or wrongly, and whether Dopers like it or not, we tend to think that this is detrimental to magic as a whole, and especially to those who entertain people with magic for a living.
Now, Derleth is of course perfectly entitled to say ‘Unsubstantiated claim’, or to suggest that the ‘No true Scotsman’ fallacy may be present. There is nothing I can do to substantiate what I’m saying here, and I’m sure it’s as obvious to Derleth as it is to me that there is no mechanism by which it could be substantiated. I’m simply reporting from 25-30 years of experience. All I can say is that if Derleth were to spend a long, long time getting to know the magic trade and the people in it, as I have done, I believe he would eventually conclude that the description I’ve given above - of how the majority of magicians view the subject of public discussion of magic secrets - to be an accurate one.
So what should the SDMB policy be on magic secrets?
In the past, when people have started threads about how such-and-such a trick is done, I have felt it was relevant and helpful to point out that ‘those who know are unlikely to tell’, and perhaps to point out that some of the responses are not well-informed ones. However, I’ve been flamed a little for doing so. I’ve been accused of deliberately leading false trails and giving out disinformation (something I have never knowingly done), and I’ve also seen my intentions mis-characterised as a rather smug and insufferable form of ‘I know but I’m not telling, na na nana na’. I have apologised to Dopers who felt that this was what I was doing - it wasn’t my intention.
The point here is not one of censorship, but of pragmatism. I am not advocating a policy that says ‘You can’t discuss how magic tricks are done on the Dope’. I’m saying that it’s largely futile to do so, for the reasons given above: the people with the facts generally don’t tell.
My own opinion is that if someone posts a question here about how a trick is done, the appropriate response is for someone like myself (or others in a position to know) to refer the OP to a source where they can pursue their interest - albeit they will have to go to some time and trouble to do so. This is what happened with a recent thread about card manipulations and flourishes, where the question was asked and answered without any fuss, heat, invective, argument, flames or policy discussions.
But that’s just my opinion.