People who are not eligible AT ALL for temporary entry to NZ are the ones mentioned here as being ineligible for residence, also.
http://www.immigration.govt.nz/opsmanual/35057.htm So the instructor was right, that a criminal record of a certain kind can exclude someone permanently.
The list I know of that mentions drunk driving is this
http://www.immigration.govt.nz/opsmanual/35058.htm, which sets down that anyone convicted of it within the previous five years cannot be granted residence without a character waiver.