"I used to be good with faces - hopeless with names but good with faces - but I can't remember any now."
Bumping into those who have appeared before him comes with the territory.
The amazing thing is they don't seem to hold grudges. I mean look, when you are made a judge you are given the big security lecture, you don't have your name in the phone book, but I'll be running and hear 'hi judge'.
However, the familiar face of the Rotorua courtrooms won't be there much longer.
At the end of the year Judge McGuire will leave Rotorua, a place he clearly loves, swapping the court benches in Rotorua, Taupo and Tokoroa for Manukau District Court.
It's not a move he makes lightly - but there is a greater pull, a home that has been part of the family since 1865.
"All other things being equal we'd stay here forever.
"The old ancestral home at Tuakau has had tenants in it for quite a while and we need to go there to make sure it means something for our children and grandchildren."
He speaks fondly of Rotorua and the tales of his time here.
Early on having heard of Ford Block, with its Once Were Warriors reputation, he decided he had to check the area out.
"If I may say so I chose my timing well. I went for a run through Ford Block 8am on New Year's morning.
"There were still three parties going and I got invited to two."
For him, the people are a huge part of what makes the city so special - and the job so satisfying.
He credits everyone from court staff to lawyers, prosecutors, JPs, community magistrates, social services - all those working within the court environment.
The people he works with are what makes the job special, he says.
"You can find a lot of humour in this too. I've got a drawer full of funny things that have happened.
"There is some horrific stuff that happens and truth is stranger than fiction. Just when you think that you have seen or heard it all something else happens."
He spoke with a sense of pride of Rotorua's restorative justice programme - one which he said was "easily the best in the country".
"It is leading edge. From day one we included even domestic violence in restorative justice which was something which some of the academics weren't too keen about, but the runs are on the board.
"We must be getting up to 17, 18 years now of experience with this and these Te Arawa women have done the most superlative job.
"I shouldn't pick out names but you are only as good as the people around you but they are standouts."
He said with a primary justification to make "things as right as they can be for the victim", the proof of restorative justice was in the results.
"And so classically the victim gets to see this unknown monster who burgled their house and has thereby sort of terrorised them and their children is a pathetic little person who doesn't know any better."
The difference between victims who had been through successful restorative justice, and those who hadn't, was "just so stark".
"There are varying degrees of all this and beware the person who says they have the final or dead right or complete answer, but by and large the victims who go through restorative justice are way better off. And often for the first time the offender, it sinks in, 'oh jeez, I have hurt somebody, there is a person involved'."
He said sitting for so long in Rotorua, he had seen generations of defendants appear before him.
"Equally I've seen some wonderful examples of people from that sort of background who've made the decision 'nah, that's not for me'."
He said he saw "indirectly" the changes in people's lives.
"I suppose validation is this, that [defence lawyer] Max Simpkins on one occasion said to me, 'Your Honour, my client needs a good old fashioned Judge McGuire telling off'."
Among the thousands of cases there were some that had stuck in his mind.
"One I had to stop in the sentencing twice to compose myself. It was truly awful... That would easily have been the worst case."
He said his lawyer training helped prepare for the job, along with exercise.
"I guess you sort of have to have a mind like a dump truck.
"Exercise. I go for a run or I go for a ride in the forest, the old forest is very therapeutic."
While he didn't remember his first day sitting in Rotorua, he recalled the first week.
"I remember a day shortly thereafter and there was a riot in the court because the defendant was expecting periodic detention as it was then and the problem was there was some quite serious offending like street robbery of an old lady and so the sentence recommendation was just wrong."
Judge McGuire said things took a bad turn when he mentioned jail, and the defendant's colleagues decided they were going to free her then and there so there was a bit of a free for all.
He said the court taker turned around and said "Judge, I think you better leave".
While being a judge was never part of the master plan, Judge McGuire said he wasn't ready to give up yet, even after "that big health scare" two years ago.
That big health scare was his diagnosis with colorectal cancer, but he described himself as "utterly blessed" with the treatment he had.
"It was pretty dire there at the beginning. I have major tests twice a year and in August of this year had scans and blood tests and so on and there was no evidence of disease."
He said following his health scare he wanted to "get back on the horse".
Besides, he believes he still has a bit to offer before retirement rolls around, as it will in due course.
"Retirement sort of scares me a bit."