Margaret Thomsen, 72, was walking into a Bay of Plenty Countdown supermarket to do her food shopping when she noticed a dishevelled man looking at her.

She eyes the man's long toenails and rough clothes, and instantly feels sorry for him.

"Oh, aren't your feet freezing cold?" she says.

He explains he was driving from Starship hospital in Auckland with his dead granddaughter in his van but he's run out of petrol.

His face wracked with grief, he says all he needs is $20 to get to the urupa, the resting place for his granddaughter.

Thomsen's husband died recently. She thinks: "My husband would want me to help."

She hands the man the leash for her white poodle and walks into Countdown, telling the cashier why she needs to get cash out.

The cashier hesitates, doubting the story. A man queuing at the checkout tells Thomsen not to hand over money, and goes with her to retrieve her dog.

Unlike many handing over money to a scam also popping up in Auckland and across the country, Thomsen was stopped only by the intervention of a concerned bystander.

"That's the only reason I didn't give $20," she said. "I was very lucky."

Until she was helped, it never dawned on Thomsen she was being conned.

"What a terrible thing to say, that you'd got your granddaughter's body in the back of your van."

Thomsen was disgusted anyone could stoop so low and had lost trust in people as a result.

Sharing her story with friends, others had surprisingly similar encounters.

Sandy Ward said she heard of another incident in Welcome Bay, Tauranga, where a woman was approached by another woman needing $40 for petrol.

The cadger was still around, still asking for money, days later.

Ward said the trouble was "many people don't think the police can do anything about scammers".

Although some circulate warnings on social media, none of several victims spoken to by the Herald reported the incidents to the police.

A police spokesperson said complaints were regularly received of various such scams, but the frequency and way in which they operated varied.

Scammers could be charged under the Crimes Act, although the penalty for obtaining through false pretences varied depending on the amount of money taken.

A person convicted for taking less than $500 under false pretences could be jailed for up to three months, while those taking more than $1000 under false claims could be jailed for up to seven years. A person taking between $500 and $1000 could be jailed for up to a year.

"If you have any doubt about a call, email or approach, it is more than likely [a scam]," the police spokesperson said.

Anyone who believed they were a victim of online or in-person crime should report the matter to police.

Auckland University associate professor in psychology Dr Niki Harre said anyone approached should consider how they responded on a case-by-case basis.

"We should be careful not to take news that people are scamming others to mean that all requests for help are a scam.

"Perhaps the worst thing about these scams is that they create a sense that people asking for help cannot be trusted."

Harre suggested offering alternative ways to help, such as calling someone for them. If they were not genuine, they would likely repeat they needed money. 

"But remember that most people treat others with respect and kindness and we need to be careful to guard against being open when others are in need."

Other recent cases discovered included:

• Another Tauranga woman posted online about getting items out of her boot in a supermarket carpark when a man suddenly came up behind her, giving her a fright. The man then waffled about petrol and a baby and asked for $30. As she'd been startled, she felt vulnerable and scared so gave what he asked for. She described the man as a "scumbag beggar who preyed on vulnerable, middle-aged or older women".
• In Parnell, Auckland, a university student was approached by a man while she waited for the bus. He said his family were stranded in his car which had run out of petrol on the way to get his wallet from work. She said the man came across as well educated. The man called her phone on the spot to ensure she had his number for a bank transfer later on. "He had an answer for everything, targeted the emotions with the children aspect. My bus was due so I panicked and knew I wouldn't be able to stop thinking of it if I didn't help." She ran into the dairy by the bus stop and withdrew $30 cash for the man. Only later she realised he'd strategically asked someone who was in a rush, located handily near a store to access the cash.