Mr Mullenger admitted he has weathered a fairly slow last six years, due to the effects of the global financial crisis and the invasion of chain stores.
The tide turned on men's suits many years ago - "a suit is just brilliant for comfort and versatility" - mainly due to "the advent of the corporate suit" and a change in standards of executives' attire, he said.
The town itself has changed. When Mr Mullenger started out there was no Cameron St Mall, and there were eight independent menswear shops in the city centre.
"We all did very well but then the market changed to more off-the-rack clothes and bigger chainstores and jeans shops moved in."
But Mullenger Mens Store's range of tidy T-shirts, slightly fancy floral shirts, quality knits, smart trousers and tailored jeans kept customers coming in. There was always a nice line in accessories, and shoes did particularly well.
It paid to understand the customers, Mr Mullenger said.
"In this type of business the fashions never got too weird," he said.
"My personal taste does come into it but I sometimes pandered to the more out-there fashion. They usually ended up in a sale pretty quickly."
Thirty-eight years ago many of his customers were young guys his own age.
"Their children are now grown men and they've been coming in here too, since they were teenagers."
He said he had many favourite customers, and a few trying ones, over the years.
"We've had a long history of nice customers. Those who aren't so nice tend to be pretty awful."
