People remember how your words made them interpret themselves.

People remember conversations largely through what those conversations told them about themselves. Whether they felt competent, foolish, seen, or dismissed outlasts the content entirely. Your words become part of how someone regards themselves, which is a larger effect than most speech intends.

Before a difficult exchange, consider what conclusion the person will draw about themselves from it. You can usually make a point without the implication that they are careless or stupid. That adjustment costs nothing in accuracy and changes what they carry away.