Blissfully Ignorant, I'm in total agreement with you about the stupidity of the claim that a person's intelligence can be adduced based upon their use of colorful language.

I'm a school librarian at a school where my father once attended. When it looked a bit dodgy as to one of my own children graduating on time, he told me the story of how it was questionable as to whether he would graduate on time. It seems he had a severe case of senioritis (as we call it here), and just days before graduation, colorfully let a blue streak of language fly--at the school librarian.

Of course, it all turned out fine in the end, the whole family graduating on time with their mediocre education, and a pronounced gift for the use of colorful language.

I am forever making coy apologies to students for using colorful language in their presence. They love it because it adds an eccentric air to my librarian persona, which helps break up the monotony for them of being forced to endure the rest of the "proper" behaving staff all day every day, day in, day out...