I don't presume to speak for Google. However, as far as I know, and in my opinion, it's not the financial component in itself that would be troubling. It's the goal of manipulating Google's system for ranking.
One can buy all the links they want and convert the traffic it sends. But the moment they and their information-site partners join in a scheme to manipulate Google's system, imo Google sees itself in a position where it has to defend the integrity of it's project by taking back it's marbles and going home.
This is why I advise against purchasing advertising/links from any website that trumpets it's PageRank and the ranking benefits it conveys. When you're out in public, keep it on the downlow, put it in a paper bag and pretend it's CocaCola...
The following comment has nothing to do with the OP, I'm only commenting further on some trends that I find disturbing. This trend is the sense of entitlement that some webmasters feel that Google should ignore their link manipulation and just rank them where they feel they belong.
The flipside of that trend are the webmasters who don't provide enough content, don't sufficiently promote their sites, but feel that Google should find them and rank them anyway because the content they have is good enough. Well, in that case, Google probably should be able to discern good content and rank it according to it's merit. But it's a limitation in technology. It's technically beyond what can be done at the moment, although they say it's just around the corner with machine learning technologies such as the one behind MSN Live and Hakia.com.
But for the moment the race is generally being won by those who put a significant investment of time, money, and ingenuity into their marketing efforts. Yes, that leaves a lot of people and their businesses outside of success. But how is that different than in the offline world? And why should the rules of success and non-success suddenly change when you go online?
My advice would be to look to Amazon, TripAdvisor, Zappos, and numerous smaller and unsung sites that fly under the radar but are no less ingenious for integrating useful content into selling and reselling their products online.