"If you have a blog is of sub par quality, it will not drive traffic."

I would say what makes a blog of "quality" is defined not necessarily the professionalism of the blog, but quite possibly the "unprofessionalism" of the blog. Seems to me that it is about the authenticity of that voice, that the writer is unafraid to share his/ her opinions and is not afraid to be snarky, sarcastic, opinionated and shocking that makes people keep reading. For example there was a very well read political "blog" in San Francisco. Everyone read the thing who cared about SF politics. The author of said blog could barely string a sentence together in a proper grammatical form and the thing was riddled with misspellings. However, he ALWAYS called it like he saw it and usually nailed the situation with what the reader thought in the back of her mind without wanting to admit to it. I think it is hard to capture that authenticity if you are trying to sell or spin something.

I recently ran across the following blog on NARAL that I thought was interesting: bushvchoice.blogs.com/

For a blog to promote an established national nonprofit, it has a nice voice. It takes risks and comes off as pretty credible.