From Larry Alton, "5 Signs of a Bad Manager" at Business.com:
1. Micromanaging is the go-to approachNothing kills a business and employees’ spirit like micromanaging, but sometimes we just can't help ourselves. Many people think they’re genuinely “helping” or that nobody else can do the job quite as well as them. If you spot this in yourself, it’s kind of like being an addict—you probably won’t get better on your own.
4. They’re a meeting addictThere are many ways to foster a successful company, but being addicted to meetings just for the sake of it isn’t one of them. Meetings are often big time wasters, they can be expensive and time consuming to pull off, and some people always tend to hog these precious minutes (or even hours). It’s a sign of poor time management and a symptom of a manager who’s using fluff to make it seem like something important is happening.
Related Article: Are Technical Skills More Important than Leadership Qualities?
5. They don’t treat everyone fairly or equallyWhether it’s rampant racism or sexism, or simply the fact that the manager seems to have a “pet,” this is one of the toughest management issues to deal with. If it’s clear to you that a manager doesn’t see everyone as equals, it’s probably obvious to everyone else. This destroys company morale, makes the manager look unprofessional and will slowly poison the company. If you spot this tendency in yourself, it’s time to consider how to handle it.
There are many ways to become a better manager, but fixing what you're not doing well can go a long way.