Heres the scenario:
After a small performance to ma wee bros and a mate I decided to dip into some mentalism; specificaly the ESP experiment from the complete course.
Failed drastically....
Not the effect but the response, after card/coin/sponge tricks there is a stunned silence then drooling, but with this nothing.
Why? Heres a quote:
"I could figure out how you did that...unlike your other tricks even if I nkew I still couldnt do that....anyone can write on a peoice of paper"
Maybe I'll just stick to non-mentalism it doesnt suit my performance style (for the moment). Maybe my eyebrows are not bushy enough...

I'll take Wilson's advice:
Introduce little bits and only if you think your audience will appreciate it (I paraphrased a bit)