Police officers are too ashamed to admit their occupation to friends and neighbours because trust and respect for the force has fallen away, according to the Police Association.
The suggestions came at the association's annual conference in Wellington on Wednesday.
Delegates were told that police mistakes or misconduct are often generalised to tar all police as corrupt or incompetent.
President Greg O'Connor says officers do not go for an off-duty drink at the pub because they are vulnerable, and standing up for themselves may be career-threatening.
Mr O'Connor says police administration and the State have done little to stop the erosion of respect for the force.
But criminology professor Greg Newbold says police control their own fate and if their image is deteriorating, the force may need to look at itself first.
Police National Headquarters declined to comment.