Use the word gauche when you want to call something tacky, graceless, tactless, rude, boorish, or awkward and foolish. Have you just pointed out someone's misuse of this word? Oh dear, how gauche!
Gauche was used for a long time to refer to things that were just so wrong, it almost hurt to talk about them, like publicly asking someone why they don’t like you. That is so gauche, it could induce a cringe! Gauche is almost a gauche word, as it is comes from a French word meaning left (as opposed to right). It would be gauche to call left-handed people tacky!