According to a Google Search Engineer last year (
http://www.reddit.com/r/IAmA/comment...r_amaa/c0j2dxu), Google chooses to 'look the other way' when it comes to organic Porn search(and they specifically ignore porn as a market). As well, it is fairly well known that G likes to take an algorithmic approach to search in general and not involve human editors for a judgment call on a site unless they get a SPAM complaint or some other form of tip off. Meaning they will probably never assign a human editor, or other human resources, to look at the quality of search results for a 'porn' keyword, because they don't care if the search results for porn are good or bad. So this means to me we should have little to fear from Google sending in an infiltrator to catalog each of the adult domains which are actively trading links between each other. That's not to say that keeping these link trading platforms behind a login prompt is unnecessary, but its probably good enough to partition this information from Google's use against us.