Google+ has sadly become a large target for spammers. Even for someone like myself with a tiny fraction of the amount of followers you have gets a bunch of bullshit. For a long while I had actually hoped to use G+ openly and post my updates in the Public timeline as I do with Twitter but that lead to just too much spam. There was so much hope for a sort of happy medium between Facebook's closed network of friends social aspect and Twitter's more open-ness to spreading updates around the world. Instead it's become a mess and until it cleans up it's act it will not attract more users. Sadly I see this as a catch-22 as I doubt Google will try to clean it up until more users start to come.