You got to feel for the average webmaster these days, ranking on Google is a big deal and a big industry, it leads to a host of mal practices that can destroy websites and probably a large portion of their business. Take this hotel (hotel-jagdhof.at):
They are probably blissfully unaware Google is indexing their site as follows:
Using the really handy Firefox User Agent plugin (you could also just check the Google cache of the page), reveals the sorry state of this site:
Every page has been hijacked:
Every page links to each other with specific keywords. But they also link to other hijacked sites, for example this site for alternatives to animal testing (good cause): http://www.eusaat.org/ has the exact same issue:
The number of sites compromised to sell counterfeit goods in this example goes on, someone has been busy. Google actually stepped up their help for Webmasters against spam tactics, I would say there must be quite a few notifications for the webmasters of the sites involved in this network.