I'm not seeing too many sites (actually I have not seen any sites) who have verified authorship that are spammy or "low quality".
I would say that someone would have to be of low intelligence to pollute his Google account. Of course, you will see loads of new accounts popping up immediately from the same IPs, so I would assume Google may value older accounts more than newer ones. Of course, this is just a guess. But I will definitely keep my eyes on this, because the best way IMO for a search engine to measure quality is by who puts his name behind it. So there will most likely be some algorithm that assigns rank to Google profiles. And no, I do not believe it is based on the amount of followers (at least not exclusively), but rather history, verified ownership, influence and overall quality of sites listed.