New Zealand Prime Minister Jacinda Ardern — who flew into Sydney on Thursday night for a 24-hour visit — admits she'd struggle if she was operating in the Australian political environment.

In an interview with The Conversation, Ms Ardern said while politics in her country is very robust, "I have observed and thought, 'Gosh there is another level there in Australia'".

We've seen yet again this week how low that level can fall.

When on Wednesday Cabinet Minister Michaelia Cash delivered her extraordinary threat to, "name every young woman in Mr Shorten's office over which rumours in this place abound", she didn't just insult identifiable individuals — she also further debased our already-degraded political system.

Sorry, this video has expired Michaelia Cash threatens to reveal rumours about Bill Shorten's female staffers

Imagine if someone had said, out of nowhere and with no supporting substance, that they were ready, "to expose rumours that surround Senator Cash", Senator Cash would be justifiably outraged. She'd say: "What are you talking about?" She'd want an apology.

And yet when Senator Cash — a former minister for women, incidentally — was challenged, she initially offered only the most qualified withdrawal: "If anyone has been offended by my remarks, I withdraw".

It wasn't until Thursday afternoon that she withdrew her comments "unreservedly". There was no apology to the women.

Anyway, while withdrawals and apologies should be made when politicians behave badly (Thursday saw Kim Carr apologise for likening a Liberal senator to a member of the Hitler Youth), they shouldn't be regarded as get-out-of-jail cards for what ought not have been said in the first place.

They often do not repair the damage of the original smears, which leave their rents in the political fabric.

Politicians refuse to raise tone of Parliament

Politicians may agree, at the level of generality, that their discourse should be more civil; the tone of Parliament should be raised. Yet in practice, they simply refuse to change.

Let's not romanticise the past — the gutter was always there. But equally, let's not allow this crop of politicians off the hook, even if today's media blitz does mean we see more of the appalling moments than we are used to.

Ironically, it appears the trail from Senator Cash's remarkable outburst goes back to Malcolm Turnbull's controversial attempt to impose a stricter standard in ministerial offices, by an addition to the ministerial code of conduct.

As part of his morals lecture delivered at the height of the Barnaby Joyce affair a fortnight ago, Mr Turnbull announced his ban on ministers having sexual relationships with members of their staff.

In Wednesday's Senate estimates committee hearing, Senator Cash — who last year got into political trouble when her then-staffer told the media about a planned raid on the Australian Workers' Union office — was being quizzed about her current staff.

Two new female appointees to senior positions are from other ministers' offices.

It is claimed Senator Cash believed Labor senator Doug Cameron was about to go down the route of insinuation and that she was being protective of her staff.

Senator Cameron categorically denied he had any such intention, saying he was seeking to probe, "the web of influence from Michaelia Cash's office into agencies that are pursuing working people and the trade union movement".

Senator Cash was doubly guilty: of apparently misjudging what Labor was on about, and of a lack of restraint and nous.

Even if she did genuinely misinterpret the questioning, her tit-for-tat was a slur on one lot of women to shield other women.

Bullying? Cash a hardened political brawler

Mr Turnbull, defending Senator Cash in Parliament, accused Senator Cameron of "bullying" her. Senator Cash also invoked the bullying line. It was clutching at straws. Both Senator Cameron and Senator Cash are hardened political brawlers.

Sorry, this video has expired On February 15, Malcolm Turnbull delivered a scathing assessment of Barnaby Joyce's behaviour

Senator Cash's frequent political tactic is to default to aggression. In this case it was counter-productive as well as egregious. Just as the Government was sloughing off the debilitating Joyce saga, and trying to exploit Bill Shorten's shilly-shallying on Adani, it was again diverted.

The incident has shown the unintended consequences of the sex ban, which shines unwanted — and what's likely in most cases to be irrelevant or misleading — light on staff moves between ministerial offices.

In terms of managing individual offices, such a ban seems common sense. But when it comes to political management across government, it encourages gossipy speculation. Once again Mr Turnbull, who found himself in a corner, went too far, potentially subjecting staff who move offices to rumour-mongering.

Ms Ardern said she didn't feel such a code was necessary in New Zealand. But she added diplomatically that she was not passing judgement on what happened here.

"You're always meeting the demands that are on you as a leader at that given time, and so certainly I watched and it was a really difficult situation in Australia that's been going on over this last period," she said. That's something of an understatement.

Peter Dutton 'frustrations' excuse doesn't wash

Among those who rallied to defend Senator Cash, Peter Dutton headed off in a particularly distasteful direction — Labor figures' personal pasts.

"I think there's a frustration on the Coalition side at the moment," he said on radio. "We've sat there taking a morals lecture from Bill Shorten in relation to Barnaby Joyce over the last few weeks, and people know there is a history of problems in Bill Shorten's personal life, Tony Burke's personal life, and to be lectured by the Labor Party really sticks in the craw," he said.

"I think if we're being honest, there's a general frustration within the Parliament that you've got people like Shorten and Burke and a couple of others on the other side who are being virtuous, and I'm not sure they've got great grounds to be virtuous."

There are two obvious points to make here.

The headline "morals" lecture in the Joyce case came from the Prime Minister.

And the "frustration" the Coalition feels is less because of any Labor moralising and more because the Government is killing itself with its own mistakes.

Michelle Grattan is a Professorial Fellow at the University of Canberra and chief political correspondent at The Conversation. Originally published on The Conversation.