The very act of pulling out a notebook and jotting something down makes people nervous. I once wrote down an idea for a comic and had someone who just happened to be nearby accuse me of keeping tabs on what they were doing. I asked what they were doing that they thought I’d want to make a note of it. They didn’t want to answer.
These days, I use a notebook app on my phone. People think I’m writing an e-mail, and it doesn’t faze them. It’s odd, because I could just as easily be emailing someone to report about their activities.