durandl: (...) snooping around in your account when you are not logged in (...) And then they have valuable information about you, like what kind of games you like to buy here or even what you say to the community here. And that's one scary thought. And that's just what happened with Cambridge and FB.
This was a known fact for Facebook and Google without them "snooping" in your account (that would be breaking the law). Facebook and Google are collecting lots of data about you, your friends, and people "similar" to you. Based on that, they're proposing accurate (converting to money for them) adverts. You can disable adverts proposing based on your data on those services. I don't know if that makes them stop collecting the data. :)
They can collect data about you even without you being logged in to your Google or FB account, based on your browser cookies (for pages that use Analytics or FB/Google plugins), where you are (they could be collecting wifi IDs, IPs), which machine are you using (browser fingerprint), not to mention data from your Android smartphone, what you search for, what YouTube trailers you're watching, which pages you're viewing, what you search for on those pages. Letting GOG read your logged in profile data when you log in through it is really not a big factor in terms of data for them. :)