Note that, in the abstract, “vulgar” means “common” (as in “vulgar latin”). Indeed, its negative connotations come from that same sense: “common” people are unrefined.
I wonder if that's as big of a problem in the romance languages (which all treat left/right the same way - left = bad, right = good)
- direction
- straight ahead
- civics
- propriety
- Rude: "coarse, rough, unfinished, unlearned" (https://www.etymonline.com/word/rude#etymonline_v_16610)
- Mean: "shared by all, common, general" (https://www.etymonline.com/word/mean#etymonline_v_12495)
And even synonyms like obscene, indecent, or disgusting, which don't evoke this distinction directly, still almost always ultimately rely on separating things based on what is "good" and "clean" according to class distinctions.