I'd forgotten about the Brown Ross trick; learnt a lovely principle elsewhere; now realise how the BR trick was done. There's a very shakey aspect to how this works that has never been questioned when I've done similar for people (yes, it's easy enough for me to do!). That said (and on reviewing the effect), Brown's presentation does a wonderful job of nipping that possibility in the bud before the spec has even considered it, even without the psychological force.
Similarly, Max Maven's trick with the magazines on
Nothing had me baffled, but before I got to that part of the explanation on the disc, I read the method elsewhere.
Shirt Happens I found fantastically obvious. It's hardly changing hands for $200, but anyone who's seen as much gay pr0n as I have ought to see through it instantly.
I think it's the more esoteric principle based stuff that people have a tendancy to see right through or are completely baffled.
What bugs me is when some old and long established idea of magic is hawked as something new and wonderful. It's okay, perhaps, to market things that way to less knowledgeable folk, but if you think you're buying a new method to perform a different effect, then it becomes a rip off.