[prawn]

In my experience, if I explain that I won't sign an NDA and they don't return, I've dodged a bullet. Last one was an older guy who wanted to rebuild eBay on a strict budget and just wasn't at all comfortable talking about his idea without an NDA. I'm willing to bet, months later, he's made very little progress.

I don't think I've missed any quality opportunities with this approach.

I'm always very polite about it and explain my reasons.