Not a remotely funny one.
Sorry. It wasn’t my intention to cause butthurt.
Not butthurt, just an absurdly specific in-joke that even somebody who has been a member for 20 years didn’t recognize. To be funny, someone has to actually recognize the joke. If you make a joke, and nobody understands what you are on about, then it isn’t a very good joke, is it?
Touché. Clearly you’re the final arbiter on what’s funny and what isn’t. Thanks for your expert input.
I must say, still harboring resentment over a policy established 11 years ago by someone who is no longer even associated with the site signifies a level of butthurt that I can’t even fathom. 
Right. The OP is trying to treat these labels as though they were like the terms in zoological classification or something. That’s not how they work.
In any case, the “correct” label for a word can be disputed, at least open to debate. For example, for the word icebox, the Longman dictionary for English language learners includes the label “old-fashioned,” but Merriam-Webster does not. Maybe they don’t think it’s “old-fashioned,” or maybe they just don’t think it’s necessary to say it’s “old-fashioned” for their audience. But these things are often judgement calls, rather than scientific categories.
Vulgar - you could probably go by which words are generally allowed to be used in U-rated movies (or possibly PG), and which aren’t. A lot of vulgar words, like the ones in your OP, aren’t also slang because they’re widely used.
Slang - used in a specific area or for a specific group of people. Not necessarily widely understood outside that group of area. Most slang is not vulgar.
There’s this incomplete list of words not allowed before the watershed. Some of those words are slang, and most are considered vulgar to some degree, and you can probably easily spot which ones are slang and vulgar and which are merely vulgar or merely slang. It’s a British list so there might be some words you’re not used to hearing so often that they have to be put on a circumscribed list - I’m sure other English speaking areas have vulgar slang words that aren’t used outside that area, but not being from there, obviously I don’t know them.
The words you cited are universal among native English speakers - it doesn’t matter if they use them or not, they do know them. Common among non-English speakers too, but in some of those languages they might be slang.
As a counter-example, there’s a vulgar Hindi word for female genitals that briefly entered the British lexicon among some young people in the late 90s, and for us it was vulgar and slang. In its original language it was simply vulgar; it was too widespread and official to be slang. For us it was a slang word and definitely intended to be vulgar.
Agreed, but it’s also very off-topic (not your fault, obvs).
Your joke might have been more obvious as a joke if you’d included a link to the straight dope rule change you were making a joke about. Otherwise, even though I was around then, I had no effing clue what you meant and thought maybe google ngrams had a glitch or something.
FWIW I’m avoiding the actual f, c and s words in case they cause search problems for people on work computers. Keeping them out of the topic title was probably a good idea. They probably won’t cause problems in the body of the thread, so I’d happily use them from here on out if I’m told it’s fine.
This notion of how a certain class of people should speak is clear, but that doesn’t mean that the upper-class or educated people did not use vulgar terms in their speech, depending on the context. Code-switching is not a new thing, and vulgar language is not only used to “hurt or shock or . . . to give offense,” (as the quote from bibliophage says), but also to express strong feeling or complicity between interlocutors, and upper-class or educated people have just as frequent cause to do that as anyone else.
Obviously the Queen never swears, but I’m pretty sure other members of the royal family use the swear words in the OP. That’s how universal they are, and why they’re not slang. There are tons of swear words that would sound really weird if they said them, and they probably have their own upper-class swear words too.
Even the Queen was an Army mechanic once upon a time. Hey, when you’re a “wrench wench”, sometimes the %&$@! wrench slips and you bark your &%*#! knuckles. Of course, she was only a Princess then.
My etymological dictionary, vintage 1930s has two entries (SE means standard English):
ct, one of two SE words that cannot appear in print anywhere in the English speaking world
ft, ditto
So they are not slang but Partridge certainly wouldn’t print them in full.
I read Hamlet in high school and distinctly remember this passage. The annotated version we studied from pointed out the pun here, although discreetly enough so as not to spell out “cunt” but explicitly enough so it was clear that Shakespeare meant to do it. Playing to the groundlings, as it were.
Shakespeare had no problem spelling anything out: