"A number of staff are very distressed that they were deliberately misled as to the real purpose of the meetings," she said.
"Some of our members are even jokingly calling him the mystery shopper."
If they were aware of the man's true identity they would still have made the same remarks but phrased them differently, said Ms Doull.
The union was now considering legal action, including making a complaint to the Employment Relations Authority.
She said the method used was appalling and considered the undercover meetings with staff a breach of good faith.
University Chancellor Tom Lambie told Fairfax the council had confidence in Mr Pollard's appointment.
He said the way it was handled was "necessary to follow on this occasion".
Mr Pollard was on holiday in the New Zealand and this allowed him to carry out due diligence before accepting the position.