Google has made Google+ very difficult to avoid. Now, it is leveraging Google+ to get you more involved in selling its ads. Opting out is pretty simple. But, you need to work at it.
So, the first thing to clarify is that you don't get to be a serf in Google's kingdom if you avoid Google+. The second thing is that not wanting to be sucked into having yourself appear in ads is pretty straightforward.
Don't review stuff using Google identities is a pretty good place to start. I know you feel like a good guy. Send a note, or give a big tip, but stop reviewing stuff online.
Ignore this thing about sharing stuff with your friends. Your friends, if they are real, probably hear you carp on about what you did and how awesome it was all of the time. They are probably glad not to have to listen to you talk about your amazing experiences.
Conversely, your friends, if they are real, probably don't want to hear your whining and mealy mouthed comments about the local Subway because you may be, in their eyes, an over privileged little bitch with borderline personality disorder.
Rarely do you need to take advice from anyone you know. Remember the time your buddy told you that Liz in reception had just broken up with her boyfriend and you could go for it only for you to find out that her boyfriend was her lesbian lover in actual fact and that Liz had hated you since the first day you had said hello to her on your way in.
When we honestly ask ourselves which person in our lives means the most to us, we often find that it is those who, instead of giving advice, solutions, or cures, have chosen rather to share our pain and touch our wounds with a warm and tender hand.Henri Nouwen
Barring your inability not to share, you can simply got to your Google+ page.
Left hand dropdown menu to settings.
There's the Endorsement Sharing thing.
Go there and opt out, if you are already not opted out because of your account admin.
You don't have to thank me.