An anonymous reader quotes a report from 404 Media: Google search really has been taken over by low-quality SEO spam, according to a new, year-long study by German researchers (PDF). The researchers, from Leipzig University, Bauhaus-University Weimar, and the Center for Scalable Data Analytics and Artificial Intelligence, set out to answer the question "Is Google Getting Worse?" by studying search results for 7,392 product-review terms across Google, Bing, and DuckDuckGo over the course of a year. They found that, overall, "higher-ranked pages are on average more optimized, more monetized with affiliate marketing, and they show signs of lower text quality ... we find that only a small portion of product reviews on the web uses affiliate marketing, but the majority of all search results do."

They also found that spam sites are in a constant war with Google over the rankings, and that spam sites will regularly find ways to game the system, rise to the top of Google's rankings, and then will be knocked down. "SEO is a constant battle and we see repeated patterns of review spam entering and leaving the results as search engines and SEO engineers take turns adjusting their parameters," they wrote. They note that Google, Bing, and DuckDuckGo are regularly tweaking their algorithms and taking down content that is outright spam, but that, overall, this leads only to "a temporary positive effect."

"Search engines seem to lose the cat-and-mouse game that is SEO spam," they write. Notably, Google, Bing, and DuckDuckGo all have the same problems, and in many cases, Google performed better than Bing and DuckDuckGo by the researchers' measures. The researchers warn that this rankings war is likely to get much worse with the advent of AI-generated spam, and that it genuinely threatens the future utility of search engines: "the line between benign content and spam in the form of content and link farms becomes increasingly blurry -- a situation that will surely worsen in the wake of generative AI. We conclude that dynamic adversarial spam in the form of low-quality, mass-produced commercial content deserves more attention."