As a result he had to go into isolation.
On April 16 the man arrived at his workplace and asked the staff who were there to open the door, despite his not being required or rostered to be there.
One of the witnesses at the trial said she denied him entry because, at that time, she did not know if he had been cleared of Covid-19 or if he was allowed to be back at the facility - which was deemed an essential service.
He then asked her to open the window so they could talk, and she declined again, saying "you still have it."
The defendant explained to her he had been "cleared" and the witness, "believing in his words", opened the window.
They had some discussion about work during the lockdown and how tired he was after contracting the virus.
Giving testimony, she said the man had licked and breathed all over his fingers and wiped down the face of the window.
Judge Walker said he returned to his workplace on April 22 and tried to get into the building again.
After being refused entry, he did the same thing - breathed on and licked his fingers and wiped them on the same window.
However, this time, he also did it on his colleague's car door handles.
His manager, who also was a witness at the trial, said the man had informed her he had been cleared of Covid-19 and she had organised for him to return to work on April 22.
However, when his partner started to feel unwell days before and was re-tested, the manager told him to not return to work until they were both cleared and she had an approval from her supervisor.
Judge Walker said the defendant gave evidence and, in it, he said he believed he could go to work as he was an essential worker.
He was confused about the dates of his visits, he said.
The court heard the defendant was very remorseful of his actions, that it was a "stupid thing to do and he wished he never done that".
Judge Walker said the case would not be about his actions, which were described as insensitive, but was about if the man was allowed to be at his workplace as an essential movement.
He believed the witnesses' evidence was "honest and accurate", while the defendant was not so accurate and had difficulties in remembering dates.
Judge Walker rejected the defendant's claims that he was an essential worker and went to his work-place to check his roster.
"Clearly he had other options to obtain that information other than go his workplace at a time he was not required to. "
Defence lawyer John Fraser indicated he would apply for final name suppression and a discharge without conviction.
Judge Walker remanded the man on bail until November 23.