I highly (highly) doubt that Google spends much time reading through this forum.
The fact is that most topics that come up here are well-known vulnerabilities in Google's armor, and Google of all people is fully aware of their weaknesses. Google knows their own exploits better than even the best guru here. They also probably have their own SEO gurus activly looking for new ways to game the system so that Google can patch the exploits before people like us find them.
Google plays a game of millions, if not BILLIONS of site changes... it's not important enough to their bottom line to pick off a few hundred blackhatters here at a time by buying PBN services. That's far too small time, and would be a huge waste of man power for them. So while they could easily afford to do an NSA sytle cold-war spying campaign on forums like this, I feel they have little provocation to do so. If they did you'd see WAY more people here getting penalized. And then we'd just go underground and do what we do anyway and they would have wasted a bunch of time/money.
If you want to be paranoid then avoid using Google products like Chrome and Gmail, those are automated systems that could sniff you out without need for grad students to be sitting here 24/7 reading stupid "how do I find free proxies" posts.