However, Spearin said over the course of the festival attendees and organisers praised KYS's services.
It didn't find any substances matching the description of the brown powder at Mardi Gras.
She said KYS saw mostly MDMA come through its tents, and, of the substances that were thought to be MDMA but weren't, testers most commonly found eutylone.
Eutylone is part of the "designer drugs" group that also includes MDMA, but drug information and alert website High Alert said it is more dangerous as it looks almost identical to street quality MDMA, but produces a weaker effect.
This is dangerous as people who have bought eutylone expecting it to be MDMA may think it's weak and be tempted to take a higher dose, which High Alert said can lead to restlessness, insomnia, and eventually psychosis due to a lack of sleep.
Mitch Lowe, director of Audiology Touring - the organisers of the festival - said KYS's presence had been appreciated by both organisers and attendees.
"Safety is the number one priority for any event and having KYS present ultimately helped us improve that," he said.
Lowe hoped KYS would be able to attend Mardi Gras next year, as well as all other festivals Audiology runs, as he said its system of confidential and legal testing of illicit substances is a system proven overseas to reduce harm.
Police said no arrests were made over the course of the festival.
Central District Police said they breath-tested nearly 9000 drivers over the weekend, 13 of whom were processed for excess breath alcohol.
Just over 50 infringement notices were also issued for speeding offences over the weekend. There were no serious crashes and no deaths on the roads.
Police were pleased almost all motorists heeded the advice given by officers at checkpoints, and a low number of people were processed for excess breath alcohol.
Overall, Lowe said, the festival really stepped it up this year.
He said aside from a little rain the show ran smoothly, and that rain was not enough to dampen the mood of punters, who gave hugely positive feedback.
"The Ohakune Charitable Trust and the local community also see a massive economic benefit, which also warms our hearts."
Spearin said KYS was thankful for the support given to the service and would be happy to come back next year if it was available and invited.
"Obviously there's not too many festivals happening in the depths of winter so I imagine we should be."
