Thank you (and all the other fraysters) for the reply (s).
You are correct, the conclusion does not follow from the premise for I was not presenting a deductive argument*; rather, I was making two inductive observations: 1) 'Naughty' words, 'foul' language, 'obscene' discourse has historically derived from language used by laypersons, and 2) The offensiveness of such words becomes diluted by the frequency and migration of usage.
1) I think you admit 1 from the definition of 'vulgar' submitted in the top post. But, I would substantiate that by Chaucer's Canterbury Tales (you'll find an interesting usage of 'queynt' in there, if you look- it renders our current usage of the 'C' word and our current usage of its homophone, 'quaint', even more insulting). Dante's Inferno (one of the first works written in the vernacular) is almost pornographic in its violent imagery.
It is also interesting how current elites, attorneys and doctors, still use Latin terminology to preserve their status (e.g., "Prima facie" the "pudenda and vulva" and "habeas corpus"). Historically, Latin was the 'delicate' language for describing bodily functions and personal rights (even more interesting with regard to individual self-determination, no?). It is a 'dead' language - one that 'the strangers do not know'.
2) Special (offensive) usage of words becomes more incisive with official (or authoritative) sanction of its usage, irrespective of whether that sanction is negative or positive. The specialness of the word becomes diluted with frequent, and more malleable usage.
A good example from the article is 'fuck'. 'Fuck' is now more often used for emphasis - similar to the German word 'doch' (e.g., "I think I'm fuckin' right", or better yet: "Fucking A!"). There are good reasons to believe that Eisenhower used this word, Kennedy used this word (and it is certain that Nixon) used this word. Bush and Cheyney have used this word and it is promulgated - the word is defused because it no longer has its 'backroom' status and is used without offense to the audience frequently. It's not the end of a politician's career if the word is quoted (it might have ended Eisenhower's career if quoted in the media).
If we examine a very offensive and hurtful (and currently taboo) word, "nigger", and its current use, some interesting considerations arise. "Nigger" cannot be said by Imus, or Russert, or Bush, or Cheyney, but it can be said by 50 cent, Snoop Dog, or Kanye West, c.f., "Now I aint sayin she a gold digger (When I'm in need) but she aint messin wit no broke niggas (I gotta leave)".
"Nigger" will be appropriated by affluent white teenagers (well, it is being appropriated), and middle class teenagers because they want to be pseudo bad ass posers. In this way, hip-hop has subverted the insult - a word poor whites have used to denigrate has become a word that affluent persons use to complement (in context).
When the victimization associated with the word becomes healed (and obviously I believe transitive usage is part of the healing process), 'nigger' will go the way of 'bastard', 'son of a bitch' , or become so mundane that it is irrelevant (e.g., "sambo") or utterly uncool (e.g., "hophead" ... 'hep cat' ...'old fart').
The exclusive use of the word, however, will fortify both its significance and devisiveness.
Ultimately, the relationship between a sound (utterance) and its referent is arbitrary - established by mere social convention. The signifier is worthless without significance.
"Stick and stones may break my bones,
but names will never hurt me."
But, what do I know, I'm a 'dick head'.
*deductive arguments are only valid if they are tautologies - useful for eliminating obfuscation or 'unpacking' meanings in complex symbology.