Bill English and Jacinda Ardern go head-to-head in the final leaders debate at TVNZ HQ in Auckland

ANALYSIS: To lie as a politician is a delicate art.

You won't get far saying down is up or the sky is red (other than in the White House, that is.)

But you can massively exaggerate, assume the worst motives of your enemies as fact, and take reporters on complex logical journeys through why what you are saying is technically true.

CHRIS MCKEEN/STUFF Jacinda Ardern is not going to raise income taxes.

Here are some of the worst mistruths of the election.

National: Labour will raise income taxes

Labour has specifically and repeatedly ruled out any rise to personal income taxes.

So why is National claiming this? Their leaders argue that since Labour plan to cancel National's tax cuts - which are already in law but don't go into effect until next April - Labour are "raising taxes". So while someone on the average wage would still pay the exact same income tax that they do today, National say they will be $1000 "worse off".

Prime Minister Bill English got an honours degree in English Literature at Victoria University during the height of postmodernism in the 1980s, so his adventurous reasoning here makes some sense.

Labour: New Zealand has the worst homelessness in the OECD

This could be true, but Labour MPs don't have the evidence they think they have to back it up.

The claim comes from a recent YaleGlobal article which compared the homelessness rate of all OECD countries. New Zealand came out on top, with just under 1 per cent of people classified as homeless. Sounds like it checks out!

Well, if you read the article you'll quickly notice the line: "The absence of an internationally agreed upon definition of homelessness hampers meaningful comparisons."

CAMERON BURNELL/STUFF Steven Joyce is not going to raise GST.

The data used for that one percent figure comes from a University of Otago study of the 2013 census which defined homelessness fairly widely, including people living in cramped garages and other temporary arrangements: something many other OECD countries do, but not all.

If you think of homelessness as literally sleeping on the streets or in the car, the number was about a tenth of that.

Which, once again, isn't to say that our homelessness is necessarily not the worst in the OECD - 2013 was a long time ago - but Labour have no way of proving that.

National: There's a $11.7b hole in Labour's fiscal plan

This claim from Steven Joyce is essentially that because Labour has given itself a fairly small amount of extra money outside of new health and education spending in the next few years, the party in fact has a huge hole.

No economist agrees with Joyce on this one. Plenty of people agree Labour will have some tight budgets to run, but the hole itself appears to eventuate from a wilful misreading of Labour's numbers.

Nevertheless, it seemed to work. All of the conversation for a about a week focused on Labour's fiscal skills and the economy - a strong point for National.

Online agitators: National will raise GST to 17.5 per cent.

Yes, John Key rose GST to 15 per cent from 12.5 per cent after saying he wouldn't. But there is absolutely no indication that National plan to do this again, despite hundreds of comments and tweets suggesting the party are planning to.

Joyce himself has actually ruled it out.

Down syndrome advocacy group: Jacinda Ardern wants to allow abortion up to birth for babies with disabilities

This fake election ad using Labour's logo and slogan went round Facebook from advocacy group Saving Downs. It has nothing behind it.

Ardern says she wants to take abortion out of the Crimes Act but hasn't indicated support for anything like what Saving Downs claim.

NZ First: Cabbages will cost $18 thanks to Labour's water tax

When Labour released its water tax it was a bit unclear on exactly how high it would be, so some confusion was natural.

But once they clarified that it would be either 1c or 2c for every 1000L of irrigated water, the wildest claims fell apart.

Vernon Small worked out what the impact could be on common items: 2c to a litre of milk, 1.3c to a bottle of wine, and just 0.6c to the cost of a cabbage.

Plus, if you know anyone who would pay $18 for a cabbage, boy do we have a bridge to sell them.