How you talk about people when they leave the room is your real résumé.

People extrapolate. Anyone listening to you describe someone who is absent quietly works out what happens when they leave, and that conclusion outlasts whatever you said about the third party. It is one of the most reliable readings available, because you are not performing for the person being discussed.

Notice what you say in the first minute after someone goes. Say the thing you would repeat to their face, or say less, and let that be the standard rather than an effort.