well, to be sky or not when speak to strangers depends on the personality individuality of person they have, different culture from different regions and mostly important, what topic they have. normally, people are comparable apt to be open when talking about some common sense issue or some pleasures. and people keep sky mostly because there are sometimes shortages of trust between audiences and lecturers or the shortage of recongition, compliements from the audiences. that make the talk envrionment frozen, and eventually to be a sky talk.