+1's are linked to individual Google accounts, it's probably more effective to ban the actual accounts. Also for those who said it's bot nets, typically the way these things work is the people doing the "plussing" get paid a very small cut. See Subvert and Profit as an example from both sides of the coin.

That'd be a good idea if you are sure all the +1's are coming from illegitimate users but with the existence of botnets/malware/etc, it's very possible that the people +1'ing have no idea they are doing it.

So shadowban them instead. The kind of people who would allow their system to be compromised are not the kind of people who would care or notice if their +1's didn't count.

I don't believe you're serious. Not only is that untrue (practically everyone is insecure in some way) but it's also a non sequitur; it's not the +1ers that suffer when their clicks don't count, it's their friends, who would otherwise benefit from having better recommendations.

It's not a bad suggestion. Their friends are going to be better off without the +1s of anyone whose account is compromised by a bot net.

I don't know if the situation has changed, but every AOL user used to be behind ~20 firewalls. So banning the IP of one AOL firewall would block 5% of AOL users.

How many AOL users are there left in the world? I don't mean to imply that there aren't many, or that they're not important, I'm really curious.

Slightly old data...but I'm sure the trend is still intact: in its 2009 fourth-quarter report released to the public on February 3, 2010, AOL.com reported a total of 4.999 million subscribers in the United States. This reflected a 27% drop from its 6.879-million subscriber base for the same quarter of 2008. At its peak, AOL reported having 30 million members worldwide, according to a 2006 report published in BusinessWeek.

I believe those aren't all ISP subscribers, though, but also people who are still paying for the service via another ISP, because they don't realize AOL made it free. They used to charge something like $25/mo as an ISP, or $10/mo if you had your own ISP and just wanted to use the AOL client for email/AOL-keywords/whatever. Eventually they made that free, but not automatically--- you have to go click on something to request to be switched over to the (identical, except for support) free account, and many old AOL users either haven't noticed or haven't gotten around to it, or don't believe it. I switched my parents over about two years ago, because until then, they/I weren't actually sure they'd get to keep their email address if they dropped the paid account (as of about 4 years ago, you can).

As an aside, this holds for more users than just those using AOL. For example, corporations, mobile phone users and universities.