THERE is no definitive list of words and phrases deemed to be "unparliamentary language".
It's more a case of knowing it when you hear it. Examples previously called foul at Westminster include rat, traitor, guttersnipe and git. Coward and swine won't do either.
Above all, MPs are drilled in not accusing one another of telling lies, with even the rhyming slang "porky pie" a no-no.
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Compared to the language currently bandied around at Holyrood, it all sounds frightfully quaint.
In recent weeks, ministers have been accused of calculated deceit, lying, bullying, cover-ups, and plunging the institution into a crisis.
Labour are the principal aggressors, with the LibDems and the Tories in support. The SNP have responded with crude, scattergun counterattacks rather than seize the high ground.
As the independence referendum campaign finally gets under way, the venom and cacophony in the MSPs' chamber is more like a bear pit every day.
Even Presiding Officer Tricia Marwick, as a former SNP MSP, came under fire from Labour on Thursday after one of the rowdiest, least enlightening, First Minister's Questions on record.
Later that day, the old-school Labour MSP Malcolm Chisholm wistfully told an event: "I think the political culture in Scotland is on the slide."
And at a talk on Friday, Alex Salmond agreed with the broadcaster Jon Snow that recent debate had been "vituperative but not educative".
So is this a healthy – if noisy – part of democracy, or is the language and the conduct of the main parties now starting to backfire? Is the debate becoming a brawl that risks turning people off politics on the eve of the most important vote in their lifetime?
It started with a rammy four weeks ago about the position of an independent Scotland in the EU.
Salmond had implied on TV that he had legal advice to support his case that Scottish entry would be automatic and sidestep the euro. But then the Government admitted there wasn't any advice from its law officers after all.
Presented with a rare opening, Labour didn't just attack, they went straight to Defcon One. Paul Martin MSP issued a press release titled "Salmond a barefaced liar" which included the words "liar" and "lies" two more times each.
In case anyone missed the point, a few hours later Labour MEP Catherine Stihler issued another headlined "Lies, lies and more damned lies" which contained three uses of the word "lied", three "lies", two "lying" and one "liar", as in the phrase "a smug, barefaced liar".
Labour strategists are brutally honest about the reason for the shrill rhetoric – to get the words "Salmond" and "liar" in the same headline. "We just wanted the story up there," said one.
Mike Russell caught it next. After the Education Secretray demanded a college chair resign for covertly taping him, he was denounced as a pantomime bully.
Labour accused him of terrorising various college chairs – all conspicuously unnamed – and called for an inquiry into the cross-campus rampages with the backing of the LibDems and Tories.
Then last week, just as Russell was putting that skirmish behind him, another furore erupted after Salmond told MSPs college budgets had risen £1m this year, when they had fallen by £9.3m.
It was a shoddy mistake, and implied the First Minister didn't know if funding was up or down.
Russell and Finance Secretary John Swinney also nodded when their boss read out the duff figures, suggesting they didn't know either.
Labour promptly claimed Holyrood was in "crisis", one which was "probably the greatest challenge to the credibility of the Scottish Parliament since it was established in 1999".
Forget the resignation of First Minister Henry McLeish over his expenses or the chaos of the Holyrood project, the low point of devolution was a slip-up over £10m college funding.
It was a preposterous charge, but such is the current feral atmosphere at Holyrood, it was virtually par for the course.
The nadir was a statement from Labour's Richard Baker last week saying the First Minister "lies instinctively" – not occasionally, not when under pressure, but almost pathologically.
Baker said it after Salmond quietly changed the Official Report – Holyrood's equivalent of Hansard – after wrongly saying there were 18,000 jobs in the renewables sector not 11,000.
When Labour's Michael McMahon told Marwick, the Presiding Officer, that she was "out of order" for her handling of the issue he earned himself a one-day suspension.
As a lame diversion, the SNP attacked two Tory MSPs with windfarms on their land, saying this showed hypocrisy on the renewable jobs front.
So is this the shape of things to come?
One veteran MSP, who wanted to remain anonymous, says the current atmosphere is "inevitable" given the SNP majority and the referendum.
With Labour finding its feet again, and Salmond looking unexpectedly vulnerable, it was no surprise things were getting raw, he said.
Nor is political writer Gerry Hassan surprised.
"I think part of the mainstream debate was always going to go this way," he said.
"For a start, it's never been wonderful. What we are finding now is that a debate that was rather thin and hollow has gone back to baseness. But it was never in a good place. It was always going to be sound and fury."
But what we are also seeing is a revival of old-fashioned opposition at Holyrood.
During the last parliament, Salmond and his whips went out of their way to be consensual as they needed to survive as a minority government.
NOW, despite Salmond saying he would govern as if still in a minority, it's all about power. The SNP wield their majority like a club, winning every vote and blocking scrutiny in committees.
This has raised a lot of opposition hackles and there is a fierce thirst for striking back.
It also helps to bear in mind what a dreadful, zombie-like opposition Labour were after 2007.
In the wake of Jack McConnell's defeat, the party was so shellshocked it let Wendy Alexander be its leader unopposed. It then turned to the anaemic Iain Gray after Alexander quit a year later.
Salmond was very lucky in his enemies, and was never put under the sustained pressure he might have encountered from a functioning opposition.
That has changed with Johann Lamont and her spindoctor Paul Sinclair, an ex-tabloid reporter who worked for Gordon Brown in Downing Street and delights in a no prisoners approach to the SNP.
The personal attacks on Salmond, Russell and the rest are largely Sinclair's work, although they wouldn't have gained traction without the government making mistakes in the first place.
As to what happens next, Salmond is optimistic, believing both sides will have to rise to the occasion in the independence debate, because that is the only way to appeal to voters.
"The debate will be won by the side that puts forward a positive vision.
"Once the Yes side [do that], the other campaign will have to go into the same mode if they want to survive," he said.
He could be right.
This may be an ugly but necessary adolescent phase in which the parties grapple with the scale of the referendum, then mature before 2014.
If not, the politicians will only have themselves to blame as voters grow ever more disillusioned.
l Editorial: page 32