Mr Paulin, another uniformed officer, a Dunedin licensing inspector and a Public Health South official would then go to the bar, with the undercover "observers able to guide us to the person", via text.
The undercover officers visited six bars in total, with some bars visited twice.
He confirmed those officers were allowed to drink while on duty.
"There is case law that backs up if someone is in a licensed premises, then one drink an hour is appropriate ... otherwise you would stand out."
The behaviour of licensees and staff was largely found to be compliant. One Octagon bar was given a written warning, after serving alcohol to an intoxicated patron at 3.40am on Sunday.
If any more offending was identified with that bar, the experienced operator could face a hearing, he said.
"As soon as you raise your head above the parapet with any licensing matter, then you become subject to more scrutiny."
Mr Paulin said the district-wide operation was the first of its kind in the country, and would continue for a year.
However, Hospitality Association chief executive Bruce Robertson called the undercover operation "creepy".
"A couple of people nursing a beer while actively looking around the bar could be somewhat creepy.
"We don't think this is an appropriate use of police resourcing and we would rather they put a uniform on and be visible so everyone knew who they were."
The association had yet to receive a response from Police Commissioner Mike Bush about the use of undercover officers in such operations.
Mr Paulin said undercover officers enabled police to observe normal behaviour in a bar, as staff and management might react differently when a uniformed officer entered the establishment.
He said undercover officers also observed responsible management from security staff, bar staff and licensees.
One bar let an intoxicated man enter, and while that was disappointing, it was pleasing he was served only water.
"We know that the majority of people arrested for violent or disorderly incidents in Dunedin are affected by alcohol.
"Taking a proactive approach to ensure that our bars are operating appropriately is one of a number of actions we can take to reduce the level of alcohol harm in the community."
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