"Buyer beware" is the phrase everyone's familiar with, but these days sellers using marketplace apps might have to be wary too.

On June 5, Facebook user Azmi SanToy posted a bunch of screen shots to the Facebook group Singapore Scooter Rider. As of 11.30 am on June 6, it had over 1,000 shares.

Azmi had put up his E-Scooter for sale, a Dualtron Ultra V2 model, for $3,700.

The same model can be found for $3,790 online, albeit with a warning that it does not fulfil the "maximum speed, width and weight limit as per the physical criteria for personal mobility devices set by LTA."

Nevertheless, Azmi managed to find a buyer, whom we'll call Brian. But getting Brian to pay up would prove to be harder than expected.

The post appears to have been removed, but Azmi's unfortunate experience is also a good reminder of how you can spot a potential scammer online.

1. No cash upfront

Brian was unable or unwilling to pay the full amount upfront. Instead, he tried to offer a smaller amount of cash, plus his laptop in exchange.

But Brian couldn't pay the smaller amount of $2,000 upfront either, and asked to pay in instalments.

2. Changing the terms

There's a famous scene in the Star Wars film The Empire Strikes Back when Darth Vader informs Lando Calrissian that he is altering the terms of the deal they previously agreed upon.

That's when audiences knew that Vader was an irredeemable villain. Once you've agreed to a deal, you shouldn't try to change it.

Similarly, Azmi told Brian that he would agree to be paid in instalments if Brian provided a copy of his father's NRIC, for "security".

Brian agreed, then later said he could not get hold of his father's NRIC as his parents didn't know about the transaction.

Azmi makes a good point -- how was Brian going to hide the E-Scooter from his parents?

If that wasn't enough, it turned out that the Macbook Brian had offered in part-exchange wasn't working properly either.

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3. Not responding

Another bad sign is when the person you're trying to get money from suddenly clams up and doesn't respond to your texts.

Note that a new character is being added to the mix -- Brian's friend, who supposedly owes him money.

If Brian's friend pays up, then Brian can pay the money he owes to Azmi, and everything will be fine.

4. Details details

By now Azmi was beginning to lose his temper, and had warned Brian that he was thinking of making a police report.

Brian came back with a story featuring a new character -- his uncle -- who supposedly took the money he raised to pay for the E-Scooter.

Brian also told Azmi that he was chasing a female friend of his who owed him $2,000.

He didn't specify if this was the same friend who owed him money, whom he earlier referred to as "him". This new friend was asked to transfer the money she owed Brian directly to Azmi.

Unfortunately, that didn't happen.

Bro counter

Another bonus sign that you're dealing with someone not on the level is their excessive use of the word "bro", or other similar terms of endearment.

In the exchange between Azmi and Brian, Brian called Azmi "bro" no less than 51 times, and "bruh" twice.

Takeaways

In general, if you're selling something online, it's not ideal to hand over the item if the payment has not been made in full.

But if you're buying something online, then there's an even simpler rule of thumb -- don't buy anything that you can't afford.

Top image adapted from Azmi SanToy's Facebook post.