It is, kinda. But there is a pretty big problem: people sought to pollute that great idea by identifying the "puzzle-word" and typing offensive terms instead. As long as the controller word is okay, the captcha will accept your login/comment/whatever. How it worked and how people took advantage for lulz is pretty good explained in →this VERY NSFW picture.
If it helps, the guy who developed recaptcha was aware of the issue and made sure that any entries containing that word were ignored: See this reddit AMA.
It is, kinda. But there is a pretty big problem: people sought to pollute that great idea by identifying the "puzzle-word" and typing offensive terms instead. As long as the controller word is okay, the captcha will accept your login/comment/whatever. How it worked and how people took advantage for lulz is pretty good explained in →this VERY NSFW picture.
Kinda sad, actually.
If it helps, the guy who developed recaptcha was aware of the issue and made sure that any entries containing that word were ignored: See this reddit AMA.
Yep, anything that is crowd sourced can easily be exploited. Sadly, the only error here is the human error.