A fly may sting a stately horse and make him wince; but one is but an insect, and the other is a horse still.
It's not a slam at you when people are rude — it's a slam at the people they've met before.
People who treat other people as less than human must not be surprised when the bread they have cast on the waters comes floating back to them, poisoned.
The only cure for contempt is counter-contempt.