An idea I thought of, if you're performing to a group of people who are likely to heckle you, is to begin the trick by saying that you have absolutely no idea how the trick works and you don't want anyone telling you.

Now you are fully justified to stick your fingers in your ears and start shouting, "La la la la la I'm not listening la la la..." if they start giving away secrets. That should usually stop them.

NOTE: Using this idea is only advised only if you can do the trick well. People should only be saying that they know how the trick's done because they are aware of the sleights that you are using, even if you are doing them well - not because you screwed the trick (or part of it) up.

I suggest not perfoming for people who will heckle you.

Also, don't draw attention to the specs that you expect them to try to figure out the effect. Don't mention it.

Just ignore people who do that. When you gain more experience you will have to deal with it less and less.