However, these reviews can be manipulated by sellers to make their products look more attractive, so it’s crucial to be able to spot the fakes from the genuine ones.

“Our investigation has uncovered popular Black Friday product categories [tablets, smartphones, headphones and phone accessories] that are littered with fake and suspicious reviews – suggesting that deals that look too good to be true often are. This leaves shoppers at risk of being misled into buying poor quality and potentially dangerous products online.

“With people more reliant on online shopping than ever before due to the coronavirus crisis, it’s vital that online platforms step up and do more to protect their users from fake reviews, otherwise the regulator must be prepared to swiftly step in with strong action.”

The regulator in question is the CMA (Competition and Markets Authority), which estimates that £23 billion worth of purchases per year are influenced by online reviews.

“Fake and misleading reviews are damaging to both shoppers and businesses, which is why we’re taking action to clamp down on such illegal behaviour. Earlier this year, for example, both Facebook and eBay committed to tackle the trade of such reviews on their sites after we demanded they address the issue”, said a CMA spokesperson.

“We are continuing to review several major websites to see whether they are doing enough to protect consumers from fake reviews. We have gathered a significant amount of evidence about their systems and are now in the process of examining it.”

But for all those lesser-known brands of phones, smart watches, headphones and other tech devices, it is much more important to pay attention not to the star rating, but what the reviews actually say.

Incentives to give 5 stars

This was for a Vankyo tablet, and there was evidence of incentivised reviews in other Vankyo tablet listings with reviewers saying they had been offered £20 to leave an honest review (but encouraging them to post five-star ratings).

One listing had almost 1,000 reviews with a 4.7-star average score. Among the reviews, one said they received a free case and screen protector 24 hours after posting a five-star review. Another, who rated the tablet three stars, said they never received the ‘review gift’ that was offered.

A suspiciously large number of reviews

This applies especially if the brand is unknown: it’s unusual for so many buyers to leave 5-star reviews in a short space of time. Which?’s investigations highlights a pair of earphones from Pro-Elec with over 1,000 reviews in six months, 92 percent of which were 5-star ratings.

Keep an eye out for an unusually large number of images too. Sellers often ask reviewers to post images when asking for a positive review (usually because of one incentive or another).

Hacked accounts

A worrying number of reviewers claim their account was hacked and that the review they supposedly posted wasn’t written by them and – in some cases – isn’t even for the product in question.

Reviews that relate to a different product

If you look closely you’ll see which precise model the review relates to. In some cases this could be simply a different colour, but in others you might find that it’s for a completely different and unrelated product.

Sometimes sellers merge listings to bring positive reviews for a different – perhaps discontinued – product to a new one. Which? found that one brand, MOYAGOA, sold mobile phone accessories whose reviews were shared with multiple different products.

Independent reviews

Genuine user reviews can be useful, but your primary source for product reviews should be an independent expert which has the experience of many similar products. Naturally, the site you’re reading now is the first we’d recommend – we’ve been providing expert buying advice for well over 20 years.

You can check out our reviews here, our roundup of the best Black Friday deals and also our guide to bagging the best possible deals.

Jim has been testing and reviewing products for over 20 years. His main beats include VPN services and antivirus. He also covers smart home tech, mesh Wi-Fi and electric bikes.