Marketplace Message Scams: How to Spot and Avoid Them (UK 2026)

You listed your RTX 3080. Within minutes, a buyer messages asking whether you accept PayPal Friends & Family, whether you have a WhatsApp, and whether you could "quickly pop the price down by £20 for a fast deal." Each request is individually plausible. Together, they are a textbook scam setup.

This guide breaks down the eight most common message-based scam patterns seen on UK used-goods marketplaces — with real examples, the psychology behind each, and concrete steps to shut them down. For a broader look at buying safely, see our guide on how to avoid scams when buying used PC parts online and the companion piece on whether it is actually safe to buy used PC parts in the UK.

Why the Message Thread Is the Primary Attack Surface

Marketplaces protect users at the payment layer — escrow, buyer protection, seller verification. Scammers know this. Their goal is to migrate the transaction out of that protected layer before money moves. The message thread is where that migration happens.

Every scam pattern below shares one root structure: establish rapport → manufacture a reason to leave the platform → execute the fraud outside protected systems. Once you recognise that structure, the specific flavour of scam becomes secondary.

Scam 1 — The Off-Platform Pull

What it looks like: Within the first one or two messages, the contact asks to move to WhatsApp, Telegram, Signal, or email. The justification is always framed as convenience — "I'm rarely on here," "easier to send photos," "my notifications are broken."

Why they do it: On-platform messages can be reviewed by the marketplace if a dispute is raised. Off-platform conversations vanish. A scammer who moves you to WhatsApp then claims "I never agreed to that" without any verifiable record.

The fix: Keep every conversation on the marketplace, full stop. Legitimate buyers and sellers have no operational reason to move elsewhere before the transaction completes. Any request to do so — however friendly — is a red flag. On Koukan, every message is logged and reviewable if a dispute arises.

Scam 2 — Off-Platform Payment Requests

The most common variant after the off-platform pull. Once the conversation moves — or sometimes without moving at all — the scammer requests payment via a method that has zero buyer protection.

The rule is simple: if a payment method has no buyer protection, it benefits only the person who receives the money — i.e., the scammer. Always pay through the marketplace checkout or PayPal Goods & Services, which preserves your right to a dispute.

Scam 3 — The Overpayment / Excess Payment Scam

Common against sellers. The "buyer" agrees to your price, sends a payment — but the payment is larger than agreed. They then message to say it was a mistake and ask you to return the difference.

The mechanics: the initial payment is either fraudulent (stolen card or account), a bounced cheque, or a reversible transfer. By the time it reverses, you have already sent the "refund" from your own real funds — plus potentially shipped the item.

The fix: Never refund a payment difference outside the platform. If an overpayment genuinely occurs, instruct the buyer to issue a cancellation through the marketplace and repurchase at the correct amount. Any pressure to return money directly to a bank account is a red flag regardless of how polite the message sounds.

Scam 4 — The Fake Buyer (Information Harvesting)

Not every scam aims at your money directly. Some aim at your personal information. A "buyer" who never actually intends to purchase will ask a series of questions that seem reasonable in isolation but are designed to collect: your full name, home address, phone number, and email.

Signs of information harvesting:

• Asks for your email or phone number before making any offer
• Wants your "full postal address for insurance purposes" before checkout
• Asks which courier you use, then asks for your account number with that courier
• Confirms purchase but then goes silent — the "purchase" was only to get your address

Share your shipping address only inside the official order flow after payment is confirmed. Never in a message thread.

Scam 5 — Phishing Links Sent in Messages

A message arrives that includes a link. The pretext varies: "here's the item you mentioned," "check my other listings," "I need you to verify the payment here," or "the courier needs you to confirm your address." The link goes to a cloned marketplace, a fake payment page, or a credential-harvesting form.

How to assess a link before clicking:

Koukan will never send a link via private message asking you to verify payment, confirm your account, or re-enter credentials. If you receive such a message claiming to be from us, report it immediately.

Scam 6 — Fake Shipping and Fraudulent Tracking Numbers

A seller sends a tracking number, but the item never arrives. The tracking number may be: a real number for a different parcel (perhaps a tiny envelope to the correct address — enough to show "delivered"), a completely fabricated code, or a number from a legitimate shipment to a different recipient that is used to "prove" dispatch before the dispute window closes.

Protection steps:

• Always verify a tracking number on the courier's own website — not a link the seller provides.
• Confirm the tracking number is associated with your postcode and the expected dimensions/weight.
• If a "delivered" scan shows but you received nothing, report to the courier and the marketplace immediately — do not delay, as dispute windows are time-limited.
• Use platforms that require proof of postage before releasing funds to sellers — this incentivises real dispatch.

Scam 7 — Artificial Urgency and Scarcity Pressure

Scammers routinely inject time pressure to prevent you from doing the checks that would expose the fraud. Urgency language short-circuits rational evaluation — a well-documented principle in behavioural psychology that bad actors deliberately exploit.

A legitimate seller will wait the extra five minutes it takes you to verify their profile, check their feedback, or run a quick reverse image search on the listing photos. Pressure to skip those steps is itself the red flag, regardless of the excuse offered.

Scam 8 — Sympathy and Social Engineering

Not all manipulation is pressure. Some is warmth. A scammer who presents as a struggling student, a parent buying parts for a sick child's PC, or a small business owner in financial difficulty is deploying reciprocity and empathy — both of which lower scrutiny.

This pattern is especially common when the scammer wants to:

• Negotiate the price down significantly, then not pay even the reduced price
• Ask you to post the item before payment clears "because I really need it this weekend"
• Claim they cannot use standard payment methods "because my bank account is temporarily frozen"

The rule here is not to be cold or suspicious of everyone — it is to separate the emotional narrative from the transactional facts. Sympathy does not change the risk profile of a payment method. A bank transfer from a sad buyer is still an unprotected bank transfer.

Red Flag Quick-Reference Checklist

Run any suspicious conversation through this checklist. Two or more ticks means stop and re-evaluate. Three or more means walk away.

How Koukan's Message System Protects You

Koukan's messaging system was built with the patterns above in mind. Several protections are enforced automatically, without any action on your part:

What to Do If a Scam Has Already Happened

If you believe you have been defrauded, act fast — time matters for both platform disputes and bank recovery processes.

Summary

The used PC parts market in the UK is overwhelmingly populated by legitimate sellers and buyers. Scammers are a minority, but a loud one. Recognising their patterns — especially the eight covered here — means they spend their time on people who haven't read this guide.

For related reading, see our full guide on consumer rights when buying used PC parts in the UK and how Koukan compares to eBay and Facebook Marketplace for safety.