What price would Labor pay for elevating a man like Peter Slipper, we wondered last November. Labor’s profound lack of judgment in relying on a man with a history like Slipper’s was obvious for all to see at the time.

But then, Julia Gillard went one further and used the breathing space Slipper afforded to alienate Andrew Wilkie over poker machine reform, making trouble for the government down the track in the event Slipper, Craig Thomson or anyone other Labor MP hit the fence.

Increasingly, Gillard reminds me of Nick Greiner. Both began their premierships in majority government and ended up with hung parliaments. Like Greiner, Gillard has racked up some substantial reforms, although Greiner’s record was significantly better. But, most importantly, both seemed to lose their capacity for political judgment and began making ultimately self-destructive decisions.

But the question raised by the latest allegations about Slipper, and they remain only allegations rejected by him, is one that goes to all parties in Parliament. Why do they tolerate MPs who behave poorly, especially when it is exactly those MPs who are most likely to defect? Labor shielded the corrupt Mal Colston for years. It was only after he ratted on his party that they found the wherewithal to pursue him for his rorting of expenses.

The Coalition tolerated Slipper for years despite repeated problems with his travel expenses (including having to pay back $20,000), a string of unsavoury incidents and a defection from the Nationals to the Liberals. Queensland Labor has its own history of tolerating poor behaviour by MPs. One former Queensland state MP, Ronan Lee, faced serious claims about his treatment of staff, particularly young female staff, and disputes in his office. Lee later defected to the Greens. He later denied any wrongdoing.

Each party, in turn, faces questions about why they accepted turncoats into their ranks or rewarded them. The Howard government found shielding Colston a constant burden. Slipper is now making life a misery for Labor. Eager to claim the party’s first Queensland state MP, Bob Brown himself went to Brisbane to welcome Ronan Lee (who, incidentally, held decidedly unGreen views on abortion) into the fold in 2008, despite the Greens being warned about his history.

In each case, the lesson is the same: these MPs end up causing more trouble than they’re worth to both their originating parties and those whom they benefit with defection.

A persistent theme is that these sorts of MPs treat their staff poorly. Colston blamed his office manager (later, state Labor MP) Christine Smith for some of his travel expense rorts in 1997. Lee churned through so many staff the Queensland parliament used a temp agency to keep him supplied. Now Slipper is accused of harassing staff.

The claims against Slipper may not be proved. But unfortunately, poor treatment of staff, and particularly electoral officers, is widespread right across politics. Stories of abuse, bullying and worse come and go in the media without anyone ever connecting the dots and wondering why politicians’ offices are such toxic workplaces. There is a long list of casualties of politicians in the community, former staff members who bear the scars of their treatment. Some are unable to ever work again.

It’s not in the interests of parliaments to address the problem, and politicians prefer to pretend it doesn’t exist. And political journalists can’t be bothered stepping back and investigating whether there’s a systemic problem.