I think that being too frank is often not appropriate when dealing with strangers. Fathers often feel they have the right to say anything they want to their children because their intent is righteous. Sometimes, maybe most times, it would be better to be less frank and couch instruction in a way that is intentionally softer so the child concentrates on the instruction rather than the need for it. I think the same line of thinking applies here. Just because somebody is doing something stupid doesn't mean that they need to told it is so. It's better to skip over the insulting part and concentrate on what a better way would be. I try to convey what I do and not critique what other people do. Unless of course, I'm poking a dragon, but that's different. The dragon won't change his scales, anyway.