"Politeness" applies to the form, not to the "contents", I guess!. What is not polite is to speak to somebody about something the other is not interested of, if you use in a any way coercitive methods. Some answers here show a bit of social confusion. I state this in a "free" society where i dont expect anyone to shot me if i deal with "sensitive" subjects. And i also just expect someone to say me good bye if he/she thinks i am boring, crazy, silly, etc and of course i wont go shooting him/her if thinks i am not an interesting person.