[gRoberts84]

If setup properly, they'll follow what Recaptcha done in the early days and use multiple sources and use the common answer rather than relying on a single source.

The only issues is that if people know this, they could simply flood the internet etc with fake information and if used, it could skew the results.

Recaptcha suffered from this in the early days when people found the first word was the control (known) word and the second was the word they wanted to convert to text.

People then started putting the same offensive word in for the second word, which was accepted and is likely to have affected the results.