From preloved pyjamas to that Porsche you always promised yourself, if you've dipped your toes into the waters of either online buying or selling, you might already be aware of the dangers of getting a nasty nip from scammers.

But a new report from not-for-profit consumer champions Which? has revealed the staggering extent of this risks – with a THIRD of buyers and a FIFTH of sellers telling the consumer watchdog they have had direct experience of dodgy enterprise in the last two years.

Which? trawled the latest UK Finance data to discover that purchase scams are the number one type of authorised push-payment fraud – in what is a growing headache for the banking sector, they now accounting for 66% of all cases reported to banks.

Vinted, Amazon, Facebook, Shpok, Nextdoor, Gumtree and eBay are all cited in Which?'s research as danger spots for online activity, with more than 1,000 secondhand marketplace buyers and 1,000 secondhand marketplace sellers quizzed for the new findings.

Some 32% of buyers and 22% of sellers admitted to researchers they had direct experience of scammers.

Rocio Concha, Which? Director of Policy and Advocacy, said: "Second-hand marketplaces can be a great way to save money and shop in a more sustainable way so it's worrying that a third of buyers have experienced a scam in the last two years."

She advised caution when checking seller's reviews and profile - especially when seeking expensive goods - but added: "However, the responsibility should not fall wholly on consumers to protect themselves from scammers. Second-hand marketplaces need to ensure there are proper checks in place to prevent scammers from advertising in the first place and that any scam profiles are quickly removed."

The new research resonates with a report from the Office for National Statistics in March which flagged that nearly 43m UK adult internet users have encountered suspected scams online, while one in five of those who lost money were left over £1,000 out of pocket.

The ONS report said: "[The] majority of online users think tech firms have responsibility to act to tackle problem."

Earlier in 2024, credit rating giant Fitch Ratings predicted UK banks are likely to face higher fraud costs due to new legally binding rules which kick in this October.

The change will mean banks have to reimburse customers who fall victim to fraudulent payment scams; until that date they offer victims a variety of voluntary schemes.Which?'s research found buyers who had experienced a scam reported receiving incorrect goods (15%) or no goods at all (15%). Others said they had received an empty package (11%) or counterfeit goods (10%). Furthermore, UK Finance data showed 76,946 cases, amounting to £40.9m, were reported to banks in the first half of 2023.

The most likely site for a scam experience, the research suggested, was Depop, with 57% telling Which? they had experienced a scam when using the site. This compared to around half of visitors to Shpock (53%),  slightly fewer to Preloved (51%), and Nextdoor (51%) and 35% of Amazon Marketplace's users also confirming a bad experience. 

Gumtree recorded 29% and eBay the same figure, while 24% of Facebook marketplace purchasers and 22% of Vinted buyers had also experienced dodgy dealings in the two years to January 2024.

On the other side of the counter, research showed sellers Nextdoor users were most likely to say they had encountered potential fraudsters - with four in 10 (39%) of those surveyed telling Which? they had experienced a scam. Meanwhile, around a quarter of those selling on Preloved (26%) and Shpock (26%) and 23% on Depop had encountered trouble, plus a fifth of those selling on Amazon Marketplace (21%), 20% on Facebook and the same proportion on eBay also confirmed issues. Some 16% of Gumtree sellers and one in 10 (11%) of Vinted's traders also experienced a scam in the two years to January 2024.

Despite 85% of respondents heaping praise on Vinted as the best-rated site for both buying and selling, Which? warned it "has concerns that Vinted customers only have a two-day window for raising issues - which may explain its low ratings for complaints handling."

● Buying secondhand goods from private sellers is not as straightforward as buying items from a trader or retailer on an online marketplace, Which? advises: "The Consumer Rights Act says the goods must be as described. A seller could be in breach of contract, if it misrepresents goods - for example, by describing a second-hand item as new - or if items are not sent when a seller has taken money. In practice though, getting money back can be tricky.