I think “rudeness” is the antonym of “politeness”. “Courtesy” has broader meaning to me because it includes, in addition to “politeness”, some elements of “demeanor” which has to do with outward bearing and social niceties.
“Politeness” in my mind is relative to a context; table manners are not in the same context as greeting strangers, say, and each of those has a strong cultural componant. My son’s college roommate made huge sucking and slurping sounds while eating spaghetti because in his culture those were not important; what was important was not letting any food fall back on your plate once taken. My son ate silently, but bit off any strings left hanging and let them fall back, so both were offended. In some cultures, a large belch after dinner is expected. Some cultures shake hands, others bow; both are being polite.
Now, to direct our thoughts to “behavior” on a public and anonymous forum like this one, what is politeness in this context beyond avoidance of “rudeness”? That just begs the question: what is rudeness in this context? In my view this would be best defined by a simple pair of lists of the DOs and DON’Ts of “netiquette” vis-a-vis bbs.applescript.net, i.e. the rules of “good behaviour” here.
Why don’t you tell us what you think they should be?