Years ago (no, decades ago) my girlfriend repeated something that her English teacher said in class; and I've always remembered it when the word, "classy" comes up anywhere. And that was that anyone who uses the word, "classy" doesn't have any. Although this was a second-hand "bit of intended wisdom", I'm assuming it also applied to phrases like, "have class" and similar references to/derivatives of the term, "classy"
I have no problem with all the different dictionary definitions associated with the word, "class", but "classy" is a word that makes me cringe on behalf of the person who uses it.
Of course, considering my own generation and that of the teacher (who wasn't all that much older than my friend or me at that time), I suspect that what may have been the roots of that "saying" could have been that the generation(s) immediately before ours was exposed to a lot of "nightclub" and/or "gambling type" of culture in which words like "dames" and "broads" (and other crass terms) were used in the whole entertainment/nightclub/gambling "scene".
Then, too, since the "saying" came from an English teacher, and since I assume there's a good chance words and English were as much his "thing" as they are mine, maybe that teacher was as "tuned in to the 'aura' of words/phrases" as I tend to be. In other words, "class" rhymes with "crass" and isn't far from "brash" or "trash"; so before even considering use of "classy" by people in/exposed to "the nightclub/gambling scene" (of a previous era), the word, "classy" (when used within one context) gives off "abrasive vibes" (a negative "word aura").
It doesn't matter what the roots of that "saying" were. As far as I'm concerned it still applies (at least if someone at all cares about the kind of "vibes"/"aura" his/her own words give off.)