Thanks for all your feedback!
You have some good stuff there as ideas. Just to set the record straight again, the people who are calling out how the trick is done are basically "thinking out loud".
I know they didn't see any gimmicks or exposures of hidden objects. It is plainly because they are smart enough to understand how it works. Even if I did the illusion 100% correctly.
Here is exactly what happened. I am not revealing a secret here, because it is clearly listed on Steve Fearson's website: http://www.downloadmagic.com/invisible_thread.htm
The other night I was floating an object in mid air. I had some inspirational classical music in the background. At the beginning of the illusion I showed it in my left palm face up, and waved my right hand over it to go with the music. It was looking mysterious. When the climax of the song came, I let it float in mid air. I also let it float within inches of some of their eyes, arms and legs. Everyone was hysterically in laughter. They were loving it, and so was I. I thought it was very successfully entertaining, and this is the feedback I got:
"That is the best trick I have ever seen!"
"I have never seen that happen before"
"I know you must have been using thread to do that..."
"Can you come to my 21st and perform for me next year?"
"I have no idea how you did that."
These comments were from different spectators. Luckily the one who shouted out mid-trick about the thread was not heard by the others (because the laughing was so loud).
But please think about it, can you see my point? If they DID hear, it would have spoiled it for EVERYONE. I didn't expose anything at all, this person was just smart enough to understand the mechanics of the illusion.
Sometimes in other cases I have had the heckler reveal the answer while it was silent. That really sucked but I kept my cool and continued the trick.
So is the original comment an appropriate one?
"Please make sure that you sit back, enjoy the magic and if you do happen to know how any of these effects are done, keep it to yourself to avoid spoiling it for the rest of the audience"