I see only one quality separating good and bad managers - their confidence in their own competence. Bad managers seem to feel they lucked out in getting their job. Like it might be "found out" that they are not really qualified. Good managers are at ease in their job. They usually seem to feel the company is lucky to have them, as with some effort they could get into a slightly better job. They often do, especially after static happens at a company.

A boss goes to his own boss, and that boss gives him an unrealistic goal to be accomplished in a short time frame. The good boss remains calm and pushes back. The bad boss walks out of the meeting full of anxiety and tells his team to accomplish the impossible, quickly. This might work the first few times, but soon the competent people on the team will leave.

One of the quirks here is management is usually better off in the long run hiring bosses who will say no to them once in a while. Bosses who always say yes are more pleasant in the short term to their superiors, but they will be better off in the long term to have someone who pushes back on requests which are too unreasonable. We see blog posts here every day about how hard it is to find good engineers. Incompetent bosses who are dripping with anxiety after a meeting with their own boss, relaying marching orders for yet another death march project - good engineers do not remain under such people very long, especially in job markets like the current one.