Amazon flooded by thousands of fake 5-star reviews, consumer watchdog group says

Tens of thousands of fake five-star reviews persist for consumer tech products on Amazon, according to a British consumer watchdog.

Which?, a group devoted to informed consumer choices in the United Kingdom, issued a report on Tuesday detailing the findings of its investigation into fake reviews on Amazon. The group found that headphones, particularly from "unknown" brands, had attracted thousands of fake reviews.

Which? searched Amazon for 14 different consumer tech products, including cameras, wearables and smartwatches, and discovered that "some appear to be far more heavily targeted by potentially fake reviews and ‘unknown’ brands — companies our tech experts had never heard of," the group said.

"It took just a couple of hours to uncover more than 10,000 reviews from unverified purchasers on just 24 pairs of headphones — an easy-to-find red flag that highlights the scale of Amazon’s problem with fake reviews," the group wrote in a post detailing the findings of its investigation.

On just the first page of reviews for headphones on Amazon, 100% were unknown brands, the report said. Also on the first, page, 71% had a perfect 5-star review score and 87% of the products were unverified, or not confirmed as an Amazon purchase.

"A set of headphones by unknown brand Celebrat had 439 reviews. All were five-star, all unverified, and all arrived on the same day," the report said. "All of this could mislead shoppers into believing a product is better than it actually is."

In a statement emailed to ABC News, an Amazon spokesperson wrote, "Even one inauthentic review is one too many. We have clear participation guidelines for both reviewers and selling partners and we suspend, ban, and take legal action on those who violate our policies."

"We use a combination of teams of investigators and automated technology to prevent and detect inauthentic reviews at scale, and to take action against the bad actors behind the abuse," the statement continued. "We estimate more than 90% of inauthentic reviews are computer generated, and we use machine learning technology to analyze all incoming and existing reviews 24/7 and block or remove inauthentic reviews."

Which? then shared its results with ReviewMeta, a company that diagnoses the accuracy of Amazon reviews.

ReviewMeta "believed every five-star unverified review of the top 10 pairs of headphones when sorted by average customer review was fake," Which? wrote.

In a statement emailed to ABC News about ReviewMeta, an Amazon spokesperson wrote: "We are able to assess review authenticity by looking at data points like reviewer, seller, or product history which websites like ReviewMeta do not have access to and therefore cannot concretely determine the authenticity of a review."

Amazon has been plagued by fake review problems for a while now.

In February, the Federal Trade Commission announced its first settlement with a company that allegedly used fake positive Amazon reviews as part of its marketing plan. The suit highlighted how important five-star reviews are to Amazon sales.

In fall 2018, the company also confirmed it was investigating reports that employees took bribes for deleting negative reviews.