While G+ is a nice way to control where your content goes out to, it is now also possible to control what comes in.
Because anybody can put you in their circles (think the Facebook user with 5,000+ “friends”).
But you may not want their content.
If you click on notifications, find one with the green circle in it. Click there and you'll see everybody both in your circles and who has added you to theirs. When you see new people there, you can opt to add them, hide them so you don’t have to look at them again, or block them.
There is one guy who put me in his circles whose content is both profane and juvenile – just what I want showing on my desktop when I’m demonstrating G+, right?
Now I can block him, so his content is gone from my stream. Thank you, Google.