randle - 7:41 pm on Feb 23, 2012 (gmt 0)

I can put my hand on my heart and say that 9 of them are actively link building/manipulating the algorithm

And there lies the paradox; the more valuable a site is, the less risk the owners are willing to take relative to link building optimization techniques. The lesser the value of the site, which in reality means the lower the quality, the more aggressive the owners are willing to be. This is why the serps look the way they do; a mix of good and poor sites on the first page.

Generally what we see is a steady rise of lower quality sites due to having a risk reward metric that allows for aggressive optimization. However, those same sites usually meet with significant, and long lasting drops as opposed to the general flux of movement near the top higher quality sites endure over very long periods of time.

The allure of chasing trophy terms can be quite strong.