No it's not. It's a problem all large and free communities face.
Try looking for private communities, and the quality is much higher.
To get into these types of communities, you have to pass an interview or maybe pay monthly (I don't belong to these types, but I've heard good stuff about their quality).
e.g. want a good business community?
Maybe have a fee for $100/month, so you have people who can afford that join.
want a good programming community? Maybe have open source contribution requirements.
Or just interviews in general will filter out a lot of crappy users.