Bottom line: Perusing reviews before making a purchase is commonplace for most people on the web, but in recent years it's been tough to know what or who to trust, thanks to fake reviews becoming rife. The UK's competition regulator, the Competition and Markets Authority (CMA) has reached out to Facebook and eBay after it discovered numerous listings allowing people to buy positive feedback.

The UK's Competition and Markets Authority (CMA) said on Friday that it "has found troubling evidence that there is a thriving marketplace for fake and misleading online reviews."

In a statement, the regulator announced that they had conducted "web sweeps" in the eight-month period between November 2018 and June 2019, and during that time over 100 eBay listings were discovered that offered to praise goods or services in return for cash. Facebook too was looked into during the same time period, and 26 groups were identified offering similar false feedback.

Citing research from Ofcom - the UK's communications regulator - the CMA said that over three-quarters of British online-shoppers consult reviews before splashing out, which shows why it's so crucial that such reviews can be trusted, as vast amounts of money change hands every day in online marketplaces.

The watchdog continued: "Fake and misleading reviews not only lead to people making poorly informed choices and buying the wrong products, but they are also illegal under consumer protection law." The law in question is the Consumer Protection from Unfair Trading Regulations (2008) which sets out a number of banned practices, including prohibiting falsely representing oneself as a customer.

Many of us would undoubtedly like to think that we're savvy enough to spot illegitimate reviews - we've all seen those clusters of 5-star reviews that coincidentally all seem to use similar wording. But some people aren't so clued-in, and often fake reviews can pass for the real thing.

The CMA added that it doesn't believe either Facebook or eBay are intentionally allowing the reviews-for-sale listings, saying that "Since [it] wrote to the sites, both have indicated that they will cooperate and Facebook has informed the CMA that most of the 26 groups have been removed."