Whatever argument the MPs might have mounted would have been completely undermined by their "supping from the gambler's cup" - as National's Tony Ryall delicately put it while twisting the knife in Parliament on Wednesday.
The consequent perception is that Labour says one thing and does another. And, as oft-stated, perception is everything in politics.
To add further insult to injury, the MPs were fooling no one in lambasting the $400 million-plus project.
At some point, Labour is going to have to shift its position on the convention centre deal away from outright opposition to something more accommodating of the aspirations of the thousands without work in Labour strongholds such as South Auckland who view SkyCity's latest venture as offering the possibility of a secure job.
Just how many jobs is a different argument.
But Labour's stance on the convention centre runs counter to one of the three fundamental policy themes the party intends to hammer going into election year - namely helping to create jobs. The others are housing affordability and lower electricity prices.
The corporate box episode might seem to be little more than a flare-up in a champagne flute. But it is symptomatic of a wider strategic malaise currently afflicting Labour.
The gains that the party made in the polls earlier this year have largely evaporated. That has been replaced by a discernible sense of drift. David Shearer is once again struggling to gain profile. Sources describe working relationships in the leader's parliamentary office as "dysfunctional". Some MPs are at cross-purposes over policy. Others - notably Trevor Mallard - are consumed with making mountains out of parliamentary mole-hills. How many times can you stage a walkout from the parliamentary chamber without losing dramatic effect?
In contrast, National has enjoyed a post-Budget rebound in the polls despite a now-familiar pattern of one political crisis following another.
The message National takes from this is that as long as it gets the fundamentals right in terms of how the "Government" affects people's everyday lives, then a bit of political static and dissonance is tolerable. Peter Dunne's mid-life crisis might be interesting, but it is not relevant to how ordinary people run their lives.
So what does Labour go and do? It spends two weeks in tandem with Winston Peters thrashing the Dunne saga to death.
Little wonder Labour is not connecting with voters.
The party argues that when it comes to dancing on Dunne's political grave, it is damned if it does get involved and damned if it doesn't.
Moreover, the real target is John Key. Labour's refrain - repeated at every opportunity - is that the minority National Government is now propped up by two disgraced MPs - Dunne and John Banks - and is thus both inherently unstable and hopelessly discredited.
This attempt to cast Key's Administration in the same light as the rag-taggle Shipley Government of the late 1990s fails at the first hurdle, however.
Shipley did not have an electoral mandate to run a change agenda. Key does. It helps that his Government is also a whole lot more popular than Shipley's. Labour's claims thus ring hollow.
The blunt truth is that in terms of activity, innovative ideas, outright attack and all-round impact, the Greens are making Opposition look easy. They are running rings around Labour. They also wisely maintained a degree of perspective regarding Dunne, with Russel Norman this week questioning the value of a privileges committee hearing which is being sought by Labour.
Should the Speaker agree there is a matter of privilege, it is difficult to see what Labour hopes to achieve beyond further humiliation of Dunne - something which might end up backfiring on Labour if the public perceive the hearing to be nothing more than a show trial.
Much depends on what Winston Peters has up his sleeve. He has hinted that he has something damaging on Key.
If he has, Peters will get the credit. Labour will be the real beneficiary.
It is still a long shot. Much of Labour's current frustration flows from the intense and competitive nature of Opposition politics. Norman and Peters can promise the earth. Labour has to be responsible.
The Labour caucus is also said to be intensely frustrated with National's cynical blunting of weapons available to the Opposition - such as delaying replies to Official Information Act requests and written parliamentary questions way beyond the legal limit.
That is not an excuse for the caucus underperforming, however. While it is still far too early to be announcing policy, that should not stop the party's spokesmen and women from writing discussion papers to give some idea of the direction Labour is heading.
David Shearer's February reshuffle of his shadow Cabinet has, however, so far failed to create any sense of urgency that might suggest the party actually wants to govern.
Even if Labour looked like a Government-in-waiting, the New Zealand electorate does not seem to be in the mood for change.
In an adept tactical move, National has sought to reinforce this nationwide mindset well ahead of election year. In doing so, National is punting that by the time the serious campaigning gets under way in 2014, it will be far too late for Labour to turn around the "no change" sentiment.
National's strategy leading into election year is utterly transparent: first, stress how the party has successfully steered the country away from economic recession with the prospect now of some solid growth; stress even louder how all that will be at risk from a Labour-Greens government (or, as National likes to state it, a Greens-Labour government); make sure National holds the centre ground in readiness for any difficult issues that might arise - and thereby keeping Labour pinned down on the left - and, lastly, work on policies that appeal to women, the one group of voters more likely to detach themselves from National.
Worried that in comparison Labour is at times fixated with relative trivia, Shearer has told colleagues to focus more on the "big picture" stuff. But that does not create headlines. In its desperate attempt to gain attention, Labour has become the dog that barks at every passing car.
Meanwhile, the clock is ticking ever faster on Shearer.
