tedster - 2:17 am on Mar 11, 2011 (gmt 0)
It's good that you're wading into real data for yourself. I often see many things that cause me to rethink the accepted "Google gospel". It's true - Google spokespeople give webmaster advice that they do not consistently execute the way you'd expect, listening only to their public words.
We have a similar discussion in this thread: Is Google blind to spammy tricks? [webmasterworld.com] where I wrote up a more detailed version of how I see it. In short, Google's mission is not to run a fair and equitable contest for webmasters. Their mission is to put the best results they can in front of their users.
You often can push the envelope without any trouble. However, if a site begins to disrupt the quality of user results, especially for important queries, that's often when the alarm bells go off and something happens to the ranking. Otherwise, if their users seem happy - statistically that is, according to the machine learning they execute - many practices seem to slip by.
Another thing Google will do is just zero out the effect of some spammy practice, but not penalize for it. So the URL is not ranking BECAUSE of the spam links, but in spite of them.