For a while Google+ recommended content that your friends liked or interacted with. I once got a Google Play app recommendation that highlighted the review a friend of mine posted on it. I was TERRIFIED that it did that by default and spend the rest of the day going through ALL settings on ALL online services that allowed connecting with friends in any way.
Also, you could go to my youtube profile and could publicly see what videos I liked. A friend asked me about it and I was mortified!
For a while Google+ recommended content that your friends liked or interacted with. I once got a Google Play app recommendation that highlighted the review a friend of mine posted on it. I was TERRIFIED that it did that by default and spend the rest of the day going through ALL settings on ALL online services that allowed connecting with friends in any way. Also, you could go to my youtube profile and could publicly see what videos I liked. A friend asked me about it and I was mortified!