I hate Google. Seriously! I have seen crappy sites on the top 5 and have no quality content.
Next time you see one of those, check out how many backlinks they have. Usually these are put up by people that really know what they are doing.
Their algorithm's have something like 100 factors they score. It's hard to tell why some sites do well, and others don't.
I have a NIche Creator site that right now is a PR4 on Google. Compare this to a nice WH site I have, with a couple hundred pages of unique, quality content, that is a PR3. Sometimes you hjust never know.
But conventional wisdom says you never mix spam sites with quality (or money) sites on the same IP's or c-blocks.