For me a good community manager must have these qualities:
1) You must be knowledgeable about the project you are managing its community.
2) You must be responsive and prompt in case of query from the community
3) You must be patient and respectful no matter how rude an individual is.
4) You must be prepared to answer any question no matter how stupid or repetitive it is.
5) You must be prepared to deal with diverse individuals.
6) You must be prepared to give attention to everyone.
7) You must know when to be strict and when to inject humor into a situation. Having a sense of humor is critical.
You must always project an aura of maturity and politeness else the community will not respect you.