A similar mistake is to include your reports in speculation about potential termination of yourself. Especially if they are "The Talent", and you are not so much. I had a non-technical manager (sales background, and probably not bad at it, actually) who somehow ended up in charge of a crack engineering team as part of a re-org. When things were going badly with upper-management, she'd go with "Our heads are all on the chopping block together! You'd better perform or else!" This happened several times. Meanwhile, we were all thinking "Nope. It's just your head on the chopping block, friend." She was gone in a year.

Edit: I should say that the "we" above was the senior engineers. There were some more junior team members who were quite terrified by this speech, until we explained to them how talent (usually) works.