Google on Friday defended its search-related spam-fighting policies and denied that sites with Google ads get a free pass, though it acknowledged a recent uptick in spam and pledged to crack down more heavily on content farms.

Pointing to several recent news stories that criticized Google's search results as spammy and unhelpful, Google principal engineer Matt Cutts said in a blog post that that search quality today is "better than it has ever been in terms of relevance, freshness and comprehensiveness."

English-language spam is half of what it was five years ago, Cutts continued, though he acknowledged an uptick in spam in recent months. Cutts also admitted that Google could do more to tackle content farms, or sites with shallow or low-quality content. Google launched two major algorithmic changes last year to combat these content farm, but "we hear the feedback from the web loud and clear: people are asking for even stronger action on content farms and sites that consist primarily of spammy or low-quality content."

"We take pride in Google search and strive to make each and every search perfect. The fact is that we're not perfect, and combined with users' skyrocketing expectations of Google, these imperfections get magnified in perception. However, we can and should do better," he continued.

He denied, however, that Google ignores spammy sites that serve Google ads. "Google absolutely takes action on sites that violate our quality guidelines regardless of whether they have ads powered by Google," Cutts wrote. "Displaying Google ads does not help a site's rankings in Google; and buying Google ads does not increase a site's rankings in Google's search results."

Earlier today, another Twitter worm made the rounds via the goo.gl URL shortening service, often directing users to fake anti-virus software.