Preventing bots from filling out forms automatically is a hard task. Researchers at Google have been thinking about more effective ways of achieving this goal. You have no doubt seen those jumbled up words that you have to decipher before you can submit a form -- well, that's still to easy for bots to figure out.
Google Research is experimenting with socially adjusted CAPTCHA's which require users to orient pictures vertically. This task is different from deciphering text or audio, but in my opinion, it's not going to be a whole lot more effective.
Any of these existing techniques have flaws -- for example, evil companies are already hiring cheap labor to figure these things out all day long. Stumping robots simply isn't going to be enough.
To solve the problem, you need to make it extremely hard for robots to solve these problems, and just as difficult to outsource the work to humans.
Let's hear what you think in the TalkBack!