It's emerged some landlords with meth-contaminated houses are avoiding telling local authorities to ensure that their homes don't lose value.
Investors say having the information on their property's council file - even if the chemical residue is removed - carries a stigma, and will put buyers off.
The behaviour is not illegal, but one homeowner's association says it is "unscrupulous to say the least".
The Auckland Council's regional environmental control manager, Marcus Herrmann, has confirmed people are avoiding reporting contamination for a variety of reasons, including uncertainty about remediation requirements, and the effect on their profits.
It does appear landlords who carry out clean-up work on their properties are often in a no-win situation. According to one estimate, contamination, even if remediated, can drop a sale price up to 5 per cent.