As the author points out, the easy fix is to let users know what they just liked, or ask them to confirm.
Also I suspect this service is fairly self-regulating. Facebook users are generally careful about what they broadcast. The author gives the captcha trick used by porn sites as an example...how many people are going to broadcast their taste in porn?
> Facebook users are generally careful about what they broadcast.
Seriously? Maybe among your tech-savvy friends, but the majority of Facebook users have no idea what they're doing when they type something into the box and click "Share."
A few minutes over at http://failbook.com/ is enough to point that out, and those are just the egregiously bad / hilarious cases.
I see this story come up a lot, but according to reCAPTCHA, it's an urban legend. There is not really any evidence that spammers actually do this at all, let alone do it on a meaningful scale.
Unless my memory is playing tricks on me, I recall Luis Von Ahn mentioning this as an example of ways people had attempted to defeat his system at a talk of his several years ago. He may have been talking about theoretical attacks and not actual ones, but I'm on my phone now and can't effectively dig for a video if one exists.
Also I suspect this service is fairly self-regulating. Facebook users are generally careful about what they broadcast. The author gives the captcha trick used by porn sites as an example...how many people are going to broadcast their taste in porn?