What's Really Happening on Google+?

Every few days I get an email that someone new has put me in their circle on Google+, which I find very confusing because I don’t do anything. My last Google+ activity was posting a link to a Mystery Map three months ago. Before that, my previous post was a month old.That pattern of engagement seems to reflect most people's Google+ usage; barely enough to register. So I’m extremely curious why I have 162 followers on Google+. Assuming that half of them are real people, Google+ is the best place for me to put something if I want people to see (and maybe even read) it.
My lazy guess as to why I have so many followers is that Google+ has a bit of a spam problem. Since I don’t take the time to investigate these peoples’ profiles I’m not sure if they’re hawking any supplements, porn sites, or ebooks. If Twitter is a peer to Google+, spam is extremely likely.
A hopeful guess is that Google+ does a better of job of collecting interests, and that new users desperate for engagement follow me due to our mutual interest in coffee or Apple. I believe that Google+ is a ghost town populated only by new users following people as they pass through.
But regardless of how they got to be following me, following me is what they are doing. And in an attempt to measure the relative value of Google+, I will post this to my profile and Twitter. Over the next few days I will track referrals to my site, and I’ll update in a few days. May my little experiment shed some light as to what’s really happening on Google+.