leaving them too clueless aint that good. most of the time its because they think that they didint pay enough attention, but the real problem is whether or not they absorbed the whole effect. some of these ppl just want to see it again. I dont mind showing them the second time.
I like multi-phase routines. In many cases there are tricks that I get asked to do again. I'm expecting this ahead of time due to the nature of the trick. With that in mind, I find ways to design additional phase to these "do in again" prone tricks. So I respond, "watch, I'll do it again". But I don't really. I do something different that fits with the routine. I don't actually do any of the tricks twice. But doing something similar can very easily do one of two things. It can make them forget they asked you to do the trick again. Or it can make them think you just showed the same trick again (with a variation). Obviously, you didn't. Make the second one just as good or better than the first one and they accept it.
I'm not a huge Blaine fan as there are many, many other magicians I'd rather follow, but in his first special he displayed this great technique of doing a different trick (big secret, right). It was with the Dallas Cowboys (I don't know players names). One of the players said, "Hey, show him that trick where you changed the Queens into aces"...or something like that. He says "yea, I know the one you're talking about", and he does a completely different trick and they didn't ask about the first trick again. Granted, a lot of editing went on. But this works. The spectator feels like you're doing what they ask, while at the same time, YOU remain in control the entire time.