I also had this light bulb reaction to this technique! Please let me know how it works out for you, I'd love to hear your results with it!
Yeah I could see how that would throw a wrench in it. I don't think they could really say 0 unless they weren't being forthcoming with you and with themselves. Nobody cares 0 about anything going on their life. Maybe the question can somehow be phrased in a way that doesn't allow 0 to be an option. I'll think on it!