The study from German researchers found “the majority of high-ranking product reviews in the result pages of commercial search engines use affiliate marketing, and significant amounts are outright search engine optimization (SEO) product review spam.” The study evaluated 7,392 product review queries on Google, Bing, and DuckDuckGo, using product searches because they are “particularly vulnerable to affiliate marketing” and spam. The combination of affiliate marketing, SEO, and review spam muddies the waters, limiting a user’s ability to find useful and unbiased information on a product they consider purchasing.

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