The disgusting episode was just one in a lengthy list of unsavoury acts perpetrated by Deane Richard Roach.

He also swam nude at Club Lime ANU, exposed himself to children at the Stromlo Leisure Centre, and fondled his genitals at the Erindale Active Leisure Centre.

The 44-year-old even stalked a woman who tried to put a stop to his bad behaviour, and "strolled" around the registers at Coles in Greenway before urinating in the supermarket.

Roach fronted the ACT Magistrates Court for a sentence hearing on Wednesday afternoon, having pleaded guilty to 12 charges.

The offences, committed between June and September last year, included acts of indecency, indecent exposure, stalking and damaging property.

The court heard Roach, of Holt, had since taken to flashing fellow inmates while behind bars on remand.

Prosecutor Katrina Marson said Roach's pattern of behaviour indicated he "clearly thought he could act with impunity".

She said "whether it was to shock, offend, or for sexual gratification", he had targeted vulnerable people, like children and young women.

"[Roach] did not care about the right of those people to work, engage in fitness exercises ... or simply play without being exposed to his genitals," she said.

Ms Marson said when an Arthritis ACT boss confronted Roach about his conduct at Aqua Harmony hydrotherapy sessions, her efforts elicited "anger and indignation" that illustrated the 44-year-old's "sense of entitlement".

This woman, who was stalked by Roach for about a week, said in a victim impact statement that he had long been "rude" despite the organisation giving him free access to its sessions at the request of his mother.

She said Roach's offending had "worn [her] out" and made her suspicious of people, while it had "terrified" her staff.

"We do not and did not deserve to be treated like this," the woman told Roach in the statement.

"We were just trying to help you to live without so much pain, and this was how you thanked us."

Roach's barrister, James Sabharwal, said his client had been diagnosed with alcohol use disorder and was under the influence at the times of his offending.

He conceded a jail sentence was necessary, saying Roach had already served about five-and-a-half months in custody on remand in relation to these crimes.

Magistrate Louise Taylor said she planned to sentence Roach on August 6.

She described the 44-year-old's crimes as having no doubt been "extremely disconcerting" for those who were unfortunate enough to have witnessed or been victim to them.

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