There are some arbitrary divisions:
*Asking what someone does for a living is generally SAFE. Asking how much they earn is NOT.
Cultural variations can cause problems: *commenting about the cost of the furniture or the taste of a meal maybe acceptable in one society but not in another. It is difficult to generalize about what is normal, polite, or antisocial in conversational practice, as there is so much cultural variation.
*Silence, for example, varies in status. It is an embarrassment in English conversations, unless there are special reasons (such as in moments of grief). However, in some cultures (e.g labs, Danes, the Western Apache) it is quite normal for participants to become silent.
Often, who speaks, and how much is spoken, depends on the social status of the participants – for example, those of lower rank maybe expected to stay silent if their seniors wish to speak.
Even the basic convention of “One person speaks at a time” maybe broken in Antigua, for example, the phenomenon of several people speaking at once during a whole conversation is a perfectly normal occurrence.