"It sounds like a story in common sense to me. I can see the story now - you are going to run two pictures, one with his big golliwog hair and the other ... No, it's not in our interest to comment," he said.
But King confirmed he was happy to pay for his clients to look better as it could make the difference.
"If I'm defending a young guy who has been arrested and has nothing to wear except the tracksuit they give you in custody, then I will go out and buy him a shirt and some pants; nothing fancy," he said.
He did not believe judges would be influenced by appearances - but said it could be important to a jury.
"It's more about what they shouldn't wear. It's not a case of dressing them up. It's about showing respect for the court. I never tell my clients what to wear, I just tell them to wear their best gear.
"If someone who has never worn a suit before suddenly turns up in a suit and tie, it will look unnatural," he said.
King said Macdonald - found not guilty of murdering brother-in-law Scott Guy - was one client he did not have to worry about clothing as Macdonald's parents bought a number of suits.
"He has very good parents and a brother who is a police detective. It was not necessary for me to give advice on his appearance.
"Once during the trial I did tell him I didn't like one of his shirts. He had a black shirt on and he looked a bit Tony Soprano. I didn't like that look," King said.
However, the parents of at least one high-profile victim are worried at how appearances can influence the justice system.
When a 5-year-old tourist was raped at a Turangi campground, her parents were horrified by a judge's comments later that her attacker, Raurangi Marino, looked "very smart" when he appeared in court.
"We felt the judge's comment about the offender's smart-looking [appearance] was out of place. We were concerned when we read them," the girl's mother told the Herald on Sunday at the time.
Barry Kirker, a clinical psychologist who prepares reports on defendants for court, said research showed attractive defendants were perceived as more credible and trustworthy, were acquitted more often and received lighter sentences than less appealing counterparts.
Lawyers knew that grooming did make a difference, he said.
"The more respectable or conforming [the accused] looks, the more favourably a judge or a jury will look on them."
"You shouldn't wear anything that could draw negative attention to you. I don't think you should wear pinstripes. You don't want to show up your lawyer or look too arrogant."
Image expert Susana Sarmiento said only 30 per cent of our communication was verbal.
"Your image for court should be seen as important, in some cases more important than the evidence being presented about you. You are there to be judged, period," she said.
