I had dinged the bell at the walker and his wife several times, finally getting a physical response. As I passed by, the husband said angrily, "Well, that is the first time I have been belled on the trail." The wife, bless her, explained to him how great it was that someone belled as they passed, as most people passed without any notice.
And the teenager, who told me after I belled, "Couldn't you have just told us you were passing."