Following yesterdays post on the ranking of this site for negative SEO, I checked the referral phrases for yesterday, and there are a number of related phrases that are popping up like "how to push down negative posts in serp" and "how to decrease push down other sites ranking seo" (these actual search phrases that people are using).

It seems that the subject of Search Engine Manipulation (which is a generic term covering both positive and negative SEO) is quite popular, and possibly reflects the importance of search engines in maintaining brand value.