Robert_Charlton - 7:47 pm on Jul 16, 2012 (gmt 0)
I have tried to crank back a bit to no avail but their SEO guidelines still basically tell us to do what could be causing the damage.
BDW - I've heard it said by others as well that "Google made me do it", so I just reread the excellent Google Search Optimization Starter Guide you linked to, with that in mind, and I don't see where Google suggests anything that could get you into trouble.
Can you cite suggestions they make which you feel might have created Panda difficulties?
I suppose the Starter Guide could warn you more that just because something is good, overdoing it can lead to problems. So they don't say to keep exact match anchor text under blank-blank percent. They do say: "Avoid purchasing links from another site with the aim of getting PageRank instead of traffic", which IMO is fairly clear. But they don't warn against common spam techniques like keyword stuffing. That's where their Quality Guidelines come in....
These quality guidelines cover the most common forms of deceptive or manipulative behavior, but Google may respond negatively to other misleading practices not listed here.... Webmasters who spend their energies upholding the spirit of the basic principles will provide a much better user experience and subsequently enjoy better ranking than those who spend their time looking for loopholes they can exploit.
The Quality Guidelines then go on to cover individually all of the Penguin factors that I've heard about. It's a very specific list.
My guess is that the "artificial backlinks when the site was new" may be hitting a lot of otherwise pretty good sites... or that their upstream link sources had such links. Using link building techniques that got you into the problem, IMO, aren't going to help you get out of it.