Everyone is irritable or indecisive at times. But some people are so difficult that they make others' lives and work a strain. Dealing with difficult people is easier when you learn to recognize some common personality types. Then you can develop coping skills for dealing with each without trying to change them. There are seven behavior types with whom most people have difficulty.
Bullies are hostile and angry, throwing tantrums to get their way.
Gripers complain about things they don't like, but rarely try to change their situation. Very nice people seem to agree with you, but won't do what they say they will. I know better types think they know everything. They're condescending and full of themselves. Stallers put things off until someone else takes over, or until the decision is made because of the delay.