SOMETIMES IT'S THE simplest scams that catch people out. Forget the widows of West African dictators and their suitcases of blood diamonds, or the surprising Spanish lottery wins that come your way without you having to buy a lottery ticket; a number of scams which have been doing the rounds in recent months are a lot less elaborate and maybe just a little more convincing than that.

Scammers have taken to posting bogus ads on legitimate websites offering cars at knock-down prices - the only problem being that these bargains don't exist. A number of people who have contacted Pricewatch in recent weeks have had first-hand experience of this particular scam; one came within hours of being taken for nearly €4,000.

Last month, a woman got in touch to ask if she was being foolish to consider using eBay to buy a car. She'd been tempted by the extremely low price of an Audi being advertised on autotrader.ie, and the seller said they were using eBay as a money-clearing house. This high-spec 2006 A3 with very low mileage would usually sell for around €20,000, but the seller was asking just €7,000. It seemed too good to be true.

And of course it was.

Before contacting Pricewatch, our reader had e-mailed Maria, the seller listed on Autotrader, and been told she was selling the car so cheaply because she'd moved from Ireland to Spain and, as the steering wheel was on the right hand side, it was attracting no Spanish buyers. Maria asked for a 50 per cent down payment to what she described as an eBay subsidiary, and said it would be kept safely by eBay until the car arrived in Ireland, after which our reader had 14 days to test/inspect it.

WE E-MAILED the seller with a view to buying the car and were spun exactly the same yarn. We were then contacted by what was supposedly the eBay subsidiary and told to send our deposit via Western Union to a named individual in London.

While at first glance the e-mail looked genuine - with eBay branding featuring prominently - the fact that a request was made for the money to be sent via Western Union was the biggest giveaway that it was a set-up. EBay cautions all users against using such money transfers, because it is so difficult to follow the money once it is sent.

We rang the Irish mobile number listed on the ad and spoke to the poor unfortunate woman who'd unknowingly played a small role in the scam. Her number had been listed completely at random to lend credence to the ad, and over the course of three weeks she had received in excess of 150 calls from would-be buyers.

We then contacted Autotrader, who said they had policed their service as best they could and had a list of guidelines to help buyers and sellers to avoid scams. They also removed the ad from their site.

Last month in the UK, HPI, a company which checks cars' back histories, highlighted a spate of online scams similar to this one.

"A number of customers have been victims of online fraudsters, paying for vehicles that the seller claims is with a shipping company," said Nick Lindsay, the director of HPI. "However, the buyer hands over the cash in good faith and the car never turns up, leaving them seriously out of pocket.

"If the car sounds too good to be true for the price, that's probably because it is," continued Lindsay. "In some cases, buyers are prepared to fly out to inspect the car they are interested in, but the vendor always finds an excuse as to why this is not a good idea.

"As more people buy online," he said, it is important that "they don't take everything a seller says on face value, and we advise buyers to never purchase a vehicle without either seeing it themselves or having had it inspected by an independent expert."

IT'S NOT JUST buyers who are being targeted. Other scam artists, posing as would-be car buyers, contact sellers using details found online, and agree to buy their cars sight unseen. The scammer then sends a bank draft for way over the asking price, and asks the seller to refund them the difference via a Western Union money transfer. The drafts of course turn out to be fake but by the time the seller's bank confirms that fact, the "buyer" has long since absconded with the refunded money.

Another even simpler scam reported by quite a few Pricewatch readers recently involves a man with leather coats to flog. We highlighted the recent story of the reader who was walking through Dún Laoghaire when he was stopped by the driver of a car who was looking for directions to the M50.

Once the driver was happy with his directions, a conversation started and he said that he worked with an Italian leather company and was in Dublin with some samples. He showed our reader three leather jackets on the back seat of the car and asked if he was interested in any of them. He said import duty had been paid on them, which could not be recovered, so he'd be willing to sell one at a knock-down price.

Although he thought it might be a bit dodgy, our reader handed over €85 for a black jacket in soft leather, figuring that even if it was a scam, he'd still got himself a nice coat for half nothing. Except he hadn't. When he brought the jacket to a leather shop to have the sleeves shortened, he discovered that it was PVC. After we highlighted this, dozens of readers from across the country contacted us to say they'd had similar experiences.

Most weren't fooled, unlike the unfortunate Portsmouth university student who last month paid £600 (€749) for a bag of potatoes. He was approached by a man offering to sell him a laptop computer. The seller showed the student a Sony laptop in a carry case in the back of a car. After handing over the cash, the laptop bag was swapped with a similar-looking one which the student later discovered contained only potatoes.

"I would advise members of the public to refrain from buying high-value goods from people out of the back of cars or vans," a Hampshire police spokeswoman said. It's advice that's probably worth heeding.