There was a case recently were a guy running an online glasses store website found that he could make more money by being as rude as possible to his customers. The site was decormyeyes (I won't add the link here) - anyway, the merchant, Vitaly Borker (using various pseudonyms) found that the more negative comments he got online, the higher his site ranked in google. All the backlinks that were generated by news agencies reporting the story meant that his ranking improved dramatically, and his turnover and profits improved accordingly.

"I never had the amount of traffic I have now since my 1st complaint. I am in heaven" said Borker in a taunting email to a dissatisfied customer.

This is a new form of Negative SEO - not negative in the way of downgrading your competitors in the SERPs, but negative in terms of generating as much negative commentary for his site as possible.

In response to this, Google have recently announced that they are going to curb this kind of behaviour by altering its search criteria.

"In the last few days we developed an algorithmic solution which detects the merchant from the Times article along with hundreds of other merchants that, in our opinion, provide an extremely poor user experience" announced google in a recent blog post.

Google does has a 'sentiment analysis system' (basically a way of telling whether a page has negative comments against it, but this system is not widely used in the main search algorithm because if it was used, you would never find any information about high profile figures. Instead Google are using a different system to detect this form of black hat SEO (which is it really) but they are reluctant to reveal the details of how this will work.