Few things annoy MPs more than the media poking its nose into their expenses, and there are few issues with so many grey areas to poke into.
The problems go back decades through the rule of several governments. From the start, MPs have made their own rules and as they did so, they suited themselves.
The current government isn't responsible for the rules that were in place when it took office, but it is having to handle an unprecedented controversy all the same.
For this it could blame the House of Commons.
It was the scandalous state of affairs in Britain, where MPs were discovered to have been claiming huge amounts of taxpayer cash for outrageous personal expenses, that provoked scrutiny of the system used here.
It was never that bad in New Zealand, but it still raised questions which Speaker Lockwood Smith dealt with by releasing, for the first time, details of parliamentary expense claims.
That led to some interesting comparisons between the amount of domestic and international travel undertaken by MPs from different parties.
It might have ended there if The Dominion Post hadn't discovered that Finance Minister Bill English was claiming $900 a week rent for the $1.2 million house which, at that time, it was thought that he owned.
It turned out the house was owned by a family trust of which he was not a beneficiary, but questions were raised about changes to the trust and to the title of the house, which at some stage was transferred to his wife.
English didn't feel he had to disclose reasons for what were personal and family matters but the problem didn't go away.
Labour steered clear of it for several weeks, probably because it didn't want a no holds barred political scrap which had the potential to go beyond the National Party.
But it decided the controversy surrounding English's situation was too good to miss, and went on the attack in Parliament.
English had already paid back the difference between what he had claimed and what he would have been able to claim as an ordinary MP, about $12,000.
That wasn't enough and the attacks centred on his role as finance minister during the belt-tightening months of the recession and his frequent reminders that the Government didn't have any money.
So English, having had enough of it, paid back all the $32,000 he had received since becoming a minister and said he wasn't going to claim any housing allowance.
In the meantime, Progressive Party leader Jim Anderton had asked the Auditor-General to investigate his allowance. This looked like a stunt designed to keep the issue alive but the Audit Office accepted it and decided to look at the entire system.
The report is still some way off but it is eagerly anticipated. Prime Minister John Key has already changed the housing allowance, putting a cap on what can be claimed, but it is still surrounded by uncertainties.
One of the most vexed issues that has arisen is the out-of-town allowance, which has been historically paid to MPs and ministers who represent and live in electorates outside Wellington.
That seems fair. They have to live somewhere while they are in Wellington for most of the weeks when Parliament is sitting and ministers, as English pointed out, have to spend nearly all their time in the capital.
English's home is in Dipton, Southland, but Labour says that in reality he lives in Wellington and has done for years. His wife, a GP, works in Wellington and his children go to school in the city.
This is a really big grey area. How can MPs represent electorates and not live in them and spend at least some of the time among their constituents?
And as they can't live in two places at once, where is their "real" home?
This isn't likely to be resolved any time soon. English seems to have right on his side, even though it may seem he really does live in Wellington.
There was some irony in the next development. The Greens, who had held the moral high ground and demanded transparency around all the "perks" enjoyed by MPs, were caught claiming too much rent for a house owned by the party's superannuation fund in which two of its MPs lived.
This was a neat scheme. The party buys houses (the Greens own two) in which out-of-town MPs live. They claim taxpayer-funded rent allowances, which go into their super fund.
The Greens said they fixed the over charging problem -- two MPs living in one house were each claiming maximum rent -- as soon as it was discovered. But they didn't tell anyone until co-leader Metiria Turei was asked about it on TV One's Q&A programme.
The party has decided to sell the houses so there can't be any question of it gaining advantage from housing allowances.
The Greens made a mistake and paid the money back, but in all other ways no MP has actually done anything outside the rules.
For weeks, English made the point that he was being treated exactly the same as any other out-of-town MP, and he was right.
But he conceded it "wasn't a good look" and so he decided to quit the system.
The Greens must have come to the same conclusion.
And that's the real problem. It isn't going to be a good look until the system if overhauled and it can be seen that while MPs shouldn't be out of pocket, they also shouldn't be able to personally gain from it.