Most voters simply don't believe politicians when they say they don't remember something important, according to a poll.
Only 25 per cent think they are genuinely forgetful, while 65 per cent think they are making it up and 10 per cent don't know.
Some major "brain fades", as they have been termed by the politicians themselves, have emerged since the last election.
Act Party leader John Banks "could not recall" whether he took a helicopter ride to the Coatesville mansion of internet magnate Kim Dotcom in 2010.
When a hoo-haa erupted over the appointment of a childhood friend of Prime Minister John Key as head of the Government Communications Security Bureau, Mr Key "forgot" he had telephoned him in Australia to tell him about the job vacancy.
And Labour leader David Shearer "forgot" four times to declare a New York bank account containing more than $50,000 in the annual pecuniary interests register.
However, he declared it to Inland Revenue.
The question in the TV3-Reid Research poll said: "New Zealand politicians including John Key and David Shearer have been suffering from what's been termed brain fades - where they forget important details. Do you think our politicians are genuinely forgetful or making it up or don't know."
Green Party supporters are the most doubtful, with 82 per cent believing they are making it up. They are followed by New Zealand First supporters (74 per cent), Labour supporters (73 per cent) and National supporters (52 per cent).
National supporters are the most trusting when MPs say they don't recall, with 36 per cent believing them, followed by 19 per cent of New Zealand First supporters, 18 per cent of Labour supporters and only 14 per cent of Green supporters.