An investigation is under way into a realtor possibly distorting suburb boundaries, as the latest valuations show property prices can halve across adjacent areas of Auckland.
The Real Estate Agents Authority said this week it had received its first complaint relating to what some people describe as "vanity suburbs" - houses being touted as being in a more desirable suburb than they really are.
"A decision is not likely for another couple of months, as it is still under investigation," said a spokeswoman.
"We take this kind of behaviour very seriously and would be very interested in knowing of any other instances of this kind."
The authority was set up two years ago amid a tightening of regulations in the industry. There is now little tolerance for real estate agents' blurring the divides between suburbs, which in places can be stark.
Quotable Value research director Jono Ingerson said homeowners frequently complained about their address in QV's database.
"We get lots of complaints from people saying it says they're in Glen Innes but they're really in St Heliers.
"I have to say sorry, you're on one side of the street and St Heliers is on the other and those are the boundaries. It always happens."
According to the Quotable Value website, number 2 Apirana Ave is in St Heliers; number 4 is Glen Innes.
Properties in St Heliers have an average value of $918,611 - almost $500,000 higher than in Glen Innes.
South of the CBD, Mt Eden and Mt Roskill have an average price gap of $400,000 as they straddle the north and south of Landscape Rd.
Adrienne Gooch, the principal at Ray White Mt Eden Village, said people often wanted to call the fringes of Mt Roskill by other names - including Mt Eden, Lynfield, Hillsborough and even Epsom.
"That's probably one key area. There are all sorts of other areas around there that don't necessarily give you a higher price, but do get more people to open homes and attract buyers," Ms Gooch said.
The name of a suburb often gave potential buyers distinct impressions of a listed property.
"We've got one at the moment that's 'Avondale Heights' - [because] there's Avondale down by the railway lines and there's Avondale up on the hills," Ms Gooch said.
"It does make a difference... But we are really careful not to misrepresent anything."
Harcourts Remuera company director Stu Jenner said he covered a wide area including Remuera, St Heliers, Mt Wellington, Ellerslie and everything in between, but all his listings followed council records.
"We had one recently asking, is it Greenlane? Is it Epsom? But I'm very clear - it was Greenlane," Mr Jenner said. "Or with Meadowbank - people say, maybe it's southern Remuera?"
Over his 25-year career, the blurring of boundaries had faded away along with a growing awareness of the Fair Trading Act and more recently the establishment of the Real Estate Agents Authority.
However, not all councils define suburb boundaries, so property services such as Terralink have taken to following the lead of the Fire Service, which has its own definitions.
In either case, the boundaries do not always fall in line with popular conventions.
Mr Jenner said he lived in Mt Eden but a neighbour two doors down called it Epsom - while Pizza Hut put the address in Three Kings.
QV rated Herne Bay as the most expensive Auckland suburb at $1.7 million for the average property and Otara the cheapest at just under $240,000.
Economists predicted yesterday that house prices would continue rising next year despite claims in Economist magazine that the New Zealand property market was overvalued by 25 per cent.
* Epsom (for Greenlane)
* Remuera (for Meadowbank)
* St Heliers (for Glen Innes)
* Mt Eden (for Mt Roskill)
* Ponsonby (for Grey Lynn)