^^ What you can do in response to the above:
For Google+ make sure you turn shared endorsements off.
In Facebook, hit the gear symbol on the top right of the screen and choose “Accounting settings.” Over on the left pane, click the “Ads” option. At the bottom of the page you should see a selector for “Pair my social actions with ads for…” Switch this to “no one.”
On Twitter? Sorry, you’re hosed. It’s a default hard lock of “on” for this concept and there’s absolutely nothing you can do about it.