How to Spot an Online Marketplace Scam Before You Lose Money

The overpayment / fake check scam

This one targets sellers. A buyer sends a check or a digital payment for more than the asking price, then explains an out — moving costs, a shipping agent, a family emergency — and asks you to send the difference back via wire or gift card before the original payment has actually cleared. The FTC's guidance on this is direct: a check can look completely legitimate and still bounce days later, and once a bank reverses a fraudulent deposit, you owe the bank the full amount, including whatever you already wired back.

The tell is almost always the same: the buyer overpays for no operational reason, then asks for money to flow back out to a third party. Legitimate buyers pay exactly the agreed price through an agreed method. Any request to refund an overpayment, especially through a wire transfer, a gift card, or a payment app, is close to a guaranteed scam.

The verification-code and phone-hijack scam

This one specifically targets sellers on Facebook Marketplace and Craigslist. A "buyer" says they want to verify you're a real person before meeting up, and asks you to read back a six-digit code that was just texted to your phone. According to a Better Business Bureau alert on this exact pattern, the code isn't a verification check at all — it's the confirmation code for a Google Voice number the scammer is registering using your phone number, which they can then use to run further scams while hiding behind your identity.

The fix is simple: never read a verification code to anyone, for any reason, no matter how the request is framed. No legitimate marketplace transaction requires you to share a one-time code sent to your phone.

Shipping and "send it first" scams

These hit both buyers and sellers. As a buyer, you might pay for an item and get a fake tracking number, or a listing simply disappears once payment clears outside the platform's protected checkout. As a seller, a "buyer" might ask you to ship an item before payment actually posts, using a payment screenshot or a since-cancelled transfer as false proof.

The common thread across both directions is the same: the platform's own payment and shipping tools exist precisely to prevent this. Anyone trying to route you around those tools — pay me directly, ship it before the payment clears, use this shipping label I'm sending you — is asking you to give up the one thing standing between you and a loss.

How to shut these down before they cost you anything

Stay inside the platform. Craigslist's own scam-avoidance guidance is built around one rule: deal locally, face-to-face, and you'll sidestep almost every scam pattern that depends on distance and remote payment.

Use a payment method with real recourse. A credit card or the marketplace's own protected checkout gives you a path to dispute a charge. A wire transfer, a gift card, cryptocurrency, or a P2P app used outside the platform's protection generally does not.

Never share a text verification code, your bank login, or your Social Security number with a buyer or seller, regardless of how they justify the request.

If a deal feels rushed, involves a payment that's oddly larger than the price, or requires you to act before you've actually met the other person, stop and re-read the listing and the conversation with fresh eyes — most of these scams fall apart the moment you slow down.

FAQ

Sources

• FTC: How To Spot, Avoid, and Report Fake Check Scams
• FTC Consumer Advice: Buying From an Online Marketplace
• BBB Scam Alert: Sellers Beware! Fake Buyers Want to Hijack Your Phone Number
• Craigslist: Avoiding Scams

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