I've posted about this before, but the situation seems to be getting worse as more real estate agents adopt Google+. They should, as it's a great tool for marketing and even for communicating with prospects and customers. However, we as a group seem to have a mindset of "if it's free and if I can tell the whole world ... I should."
Sorry, but that's not the right way to use Circles in Google+. The major value of the way Google+ works with circles is that you can segment your contacts and people you know into different Circles. So, I've got a family and close friends circle, another for acquaintances, another for Local Real Estate, and a larger worldwide Real Estate circle.
This allows me, if I want, to send out a new listing announcement or other local real estate item to those who actually are in my area simply by limiting the sharing to the Local Real Estate circle. If it's an item of general real estate interest I can share it with both Circles. I do not believe that someone in San Diego or New York is going to give a hoot about my new listing in Taos, NM, thousands of miles from either of them.
It's actually one of the most powerful features of Google+, yet as my Circles grow, and people add me to their Circles, I usually reciprocate for real estate professionals and add them to the larger global Real Estate Circle. I only add someone to the Local Real Estate Circle if I recognize their name and know they're actually LOCAL.
What I'm finding is that suddenly as more real estate people adopt Google+ I'm getting more new listing and local promotional real estate posts in my stream. This is especially onerous since I've passed 1000 followers in my real estate circles. There's only one way to quickly deal with this, and that's immediate removal of that person from my circles with two clicks of the mouse. That's the option offered, so that's the one I use. Now, doing that means that they'll still see any Public shared items I post, but no longer will they get any items specifically shared with the Real Estate Circle.
Unlike burgers and fries, bigger isn't always better. Take a stab at using Google+ Circles the way Google intended, and you may just find that segmenting prospects from past clients, buyers from sellers, and family from everybody else will improve your results and their streams as well.