Google has cracked down on what has been described as the most ambitious attempt to unfairly influence its search rankings. And the offender? J.C. Penney.

An online search expert says the retail store benefited from a mass-scale exploitation of one of the key elements of Google’s ranking: inbound links. While the exact algorithm Google uses is a closely-guarded secret, it’s generally believed that getting links for sites that are themselves prestigious and popular carries additional weight.

However, the J.C. Penney example suggests there is a point when a sheer quantity of links overwhelms the quality side of the equation.

Doug Pierce, carrying out research on behalf of the New York Times, set out to discover when the retailer had managed to hold top spot in the rankings for almost every product-related search term going. He discovered that taking one product area alone, dresses, he was able to find more than 2,000 sites that include a reference to a dress, with that reference being a text link to J. C. Penney. The majority of the sites had nothing to do with dresses, had little content, and frankly were blatantly nothing but link farms.

Deliberately using this tactic is a violation of Google’s guidelines. But a J. C. Penney spokeswoman denied any wrongdoing, telling the Time that the company “did not authorize, and we were not involved with or aware of, the posting of the links that you sent to us, as it is against our natural search policies,” adding that it was working to take the links down.

While that may indeed be the case, it’s very obvious somebody has set out to artificially boost the company’s rankings, and the fact that it has now stopped using the services of its search engine consultant firm certainly points the finger.

And why did Google take so long to fix the problem? Well, the company points to the fact that it has 24,000 employees trying to deal with 200 million unique domains. And Google’s search guru Matt Cutts flatly denied that J.C. Penney spending $2.46 million a year on paid Google ads has any effect whatsoever on its rankings for “organic” search. It’s now taken “corrective action” that has seen the retailer plummet in the rankings for most of the relevant terms.

In a separate action, Google is also adding an extension to the Chrome browser that allows users to blacklist particular domains from appearing in the results that they see for a Google search. The company says it will explore the idea of seeing which sites users choose to block and building that information into its ranking algorithm.