When Google+ communities first came out in December all of my Google+ friends were talking about the annoying community invitations that were of no interest to them. Funny, I was getting none of those. This is coming from the guy who had his community post reshared by +Vic Gundotra and received over 1400 +1s and 600 reshares. Why wasn't every spammer on Google+ inviting me to their community?
Fast forward two months and I still get about one community invite a week. Many times zero. Why is this? Well, my friends +Lauren Sutton and +Ken Bruce were having a conversation about this and it really hit me as both of them are rather new to Google+. They are already being solicited with Community invites. I did some research and I found a way you can avoid all these notifications. First go here:
You will see:
Who can interact with you and your posts
Who can send you notifications? Learn more - Select "Extended Circles"
Voila! There you have it folks. Only those in your extended circles can contact you. I would make certain that the comments are open to public conversation if you want to get the true Google+ experience.
I hope this helps.