Which? says sellers are gaming the Amazon Marketplace system with fake reviews and other suspicious activity and, as a result, millions of customers are being misled.

The consumer champion sourced a selection of products that typify the thousands of devices made and sold by relatively unknown Chinese brands, which have become increasingly prevalent on online marketplace listings in recent years.

All of them had exceptionally high ratings on Amazon, and in some cases even the coveted ‘Amazon’s Choice’ endorsement.

Product tests

When Which? put eight of these products through its independent lab tests, three performed so badly they were rated as ‘Don’t Buys’.  Almost all of the products – headphones, vacuum cleaners, dash cams and Bluetooth speakers – fell well short of the average Which? score for product performance in their respective categories.

For example, a set of headphones made by little-known brand Yineme exhibited signs of suspicious review activity – including unusually high numbers of positive reviews, high review frequency, repetition of phrases and photos and videos often uploaded alongside reviews. The headphones had a high overall rating of 4.4 out of 5 from more than 800 reviews and an ‘Amazon’s Choice’ badge.

But Which? tests earned the product a Don’t Buy warning, with a paltry score of just 37 per cent. The tests found the sound to be ‘exceptionally poor,’ with noise cancelling rendered worthless by the poor sound quality.

Shortly after Which? reported these headphones to Amazon, the product was made ‘currently unavailable’. Amazon has also deleted customer reviews from this product en masse.

Review surges

Which? says a red flag on Amazon Marketplace listings are ‘review surges’ where a high number of reviews are left in a short space of time.

For example, a pair of Enacfire Future Plus Headphones had a near perfect average score of 4.9 out of five from a large number of reviews, with reviews almost tripling in three months.

But when Which? tested the performance of the headphones, they scored an abysmal 39 per cent and a Don’t Buy warning.  The sound quality was ‘unforgivably poor’ with an ‘incredibly tinny sound’, ‘appalling comfort’ and a substandard battery life for one listening session.

Amazon action needed

Which? believes fake reviews are being used routinely by unscrupulous online sellers to undermine honest sellers and is concerned that Amazon is failing to take strong action to stop these fake reviews.

According to the Competition and Markets Authority (CMA), online reviews influence an estimated £23bn of transactions a year in the UK alone.

Natalie Hitchins, Which? head of home products and services, said: “Customer reviews should be a helpful resource for shoppers choosing what to buy and billions of pounds are spent every year based on this feedback, so it’s vital that Amazon takes stronger action to ensure people can trust the information they see online and aren’t duped into buying poor quality products.

“There appears to be no sense of urgency from the industry to tackle this problem so it’s down to the regulator to make that happen. We urge the regulator to investigate how fake reviews are used to manipulate consumers, and to crack down on sites that fail to take appropriate action to combat this.”

Responding to Which? Amazon said it was “relentless” in its efforts to protect the integrity of reviews.

A statement said: “Any attempt to manipulate customer reviews is strictly prohibited and in the last year alone, we’ve spent over $400 million to protect customers from reviews abuse, fraud, and other forms of misconduct.

“Our objective is to catch and remove abusive reviews before a customer ever sees it and in the last month, over 99 per cent of the reviews read by customers were authentic. To do this, we use a combination of automated technology and teams of trained human investigators who analyse multiple data points such as reviewer, seller, and/or product history to determine authenticity. We use machine learning to analyse all incoming and existing reviews, and block or remove all detected inauthentic reviews.”

A Which? investigation into fake reviews on Amazon in July yielded similar findings to the latest report, while the CMA has urged eBay and Facebook to clamp down on the sale of fake product reviews through their respective platforms.