Keen gardeners all know that worm casts can spoil the appearance of a well kept lawn or gravel path. Worms seem to have messed up much of the coverage of last night’s leaders’ debate, too.

John Howard didn’t want a worm. Kevin Rudd did. When Nine wormed the debate, their feed was yanked, then their-back-up. Director of news and current affairs, John Westacott, and Ray Martin himself, have been out complaining about it.

Worm casts have muddied debate coverage, but those of us with long memories remember that John Howard didn’t perform that well in debates as PM against Kim Beazley in 1998 and 2001 and against Mark Latham at the last election. Indeed, he has been worsted in the last two. Not that it meant anything when Australia voted.

And not that it seems to matter much, anyway. William Bowe goes back to Hawke and Peacock in 1984 over at the Poll Bludger and pulls out polls on past debates. His research suggests the debate winner only won the election in 1990 and 1993.

That’s the debate. Then there’s the worm itself – and Channel Nine’s methodology.

Their studio audience were “average” Sydney voters. That’s not representative. We don’t know how they were planning to vote before the debate.

They were asked to press buttons numbered one from nine to indicate support while watching the leaders on a big screen – rather like trying to key in a number on your mobile while driving.

We know from the Roy Morgan Reactor surveys run on Crikey that Liberal and Labor voters react very differently to Howard and Rudd. There is little doubt from the initial audiences’ reaction to the opening speeches that the sample leant to Labor.

But look at the up and down “arrows” during the opening and closing statements. The Prime Minister did much better closing that opening, while with Rudd it was the other way around. From that it could be concluded that the PM is now better off than before the debate.

Perhaps he’ll take Rudd’s advice and schedule a couple more.