Google’s crawlers – automated programs that index and categorize websites for inclusion in Google’s search results – are rarely the cause of problems for search engine optimization (SEO) professionals, and indeed, are the very basis of their profession. However, on the rare occasions when something goes wrong, it’s noticeable.

An automated Google process, one search engine optimization (SEO) practitioner and blogger says, has been directing referral spam to websites, causing their search ranking to display incorrectly. The problem, according to Michael VanDeMar, is more usually associated with MSN, which used a cloak referral spammer two years ago.

However, Google provided the following response to fellow search engine optimization (SEO) blogger Barry Schwartz, when he pressed the company for a comment: "Turns out, we were running an experiment to detect malware targeting Hot Trends queries related to the Haiti crisis. Because this experiment was developed in response to an urgent situation we moved quickly and as a result used an incorrect Google search referrer which we’re now working to fix."

Canny webmasters should remain on the alert for this type of traffic, which can negatively affect search engine optimization (SEO) efforts.