The web browser Firefox will warn users when they're looking at fake reviews online. The feature follows the foundation's acquisition of Fakespot, a web service that specializes in doing just that. The retailers most prominently targeted are Amazon, Best Buy, Sephora, Shopify and Walmart, but it functions on many others.

"[Fakespot] uses a sophisticated artificial intelligence (AI) and machine learning (ML) system to detect patterns and similarities between reviews in order to flag those that are most likely to be deceptive," Mozilla product chief Steve Teixeira told Axios in a press release about the purchase. "Using Fakespot, a buyer is able to quickly see where deceptive reviews may be artificially inflating a product's ranking in search engines. As Mozilla continues to expand our work around ethical AI and responsible advertising, Fakespot is a natural fit."

There is a simpler trick: just assume user reviews are fake, incentivized, solicited, or otherwise useless, and stop worrying about their authenticity—unless they contain details or specifics about the item.

Also, ratings are completely meaningless: even the legitimate ones often refer to older versions of the product, or completely different ones.