If the character in question is a shopkeeper, they will often have occasion to say (always at the very start of a scene) “thanks Mrs Miggins, have a good day love” to some ageing bint who isn’t allowed to speak back to them, but instead gives a mute little nod before walking out of the shop.
At no point will they ever mutter “miserable arl c*nt” at this blatant display of gratuitous rudeness.