Originally posted by Classics
Penalizing crosslinking isn’t a good idea, but putting a dampening factor on the effect is a good idea, and Google already does that to some degree. Perhaps they should do more. Some people here would disagree with you.
The key here is excessive crosslinking 
not 1 or 2 links to different sites, but dozens upon dozens going to the same site(s.)
The decisionmakers at Google right now don’t give one tenth of a crap about adwords right now!
Think about it this way … If you were interested in presenting the appearance of a better / cleaner / quality product and wanted to cleanse your SERP’s for some sort of public showing – where would you start?
Well how about targeting highly competitive terms that you know are being SEO’d to death? How would you determine these competitive terms? Well you already have a gauge of sorts and that’s your AdWord product which could/should serve as a pretty good indicator of competition … and thus the terms that are most likely highly sought after.
Id turn down the $500 from 1 person, but when its 500 from 50,000 then your talking money. If I could force others to enter into that bidding war before long it would be $750 from 100,000 and so on and so on …
Others have said this is an issue regarding the “PageRank” patent which I believe Stanford has rights to. I heard stories saying Google has been more or less forced to come up with a new system and thats what we have been witnessing in real time.
Who knows – all my evidence still seems to point at a filter.