"It makes me sick," the trailblazer for equality in sport and 12-time grand slam winner told CNN of people who continue to judge female stars of the game by their looks.
King famously beat former men's world No. 1 Bobby Riggs in a clash entitled "Battle of the Sexes" back in 1973 -- a victory that was seen as a huge leap forward for women's rights.
And she told CNN that 42 years on from that landmark event, it can often appear as if attitudes in tennis have barely moved an inch.
"When I played Bobby Riggs, do you realize that [former commentator] Howard Cosell talked about my looks the whole time?" she explained.
"And they're still doing the same thing. They still talk about their looks."
The 71-year-old's roll call of achievements in equality terms is hugely impressive.
She was instrumental in forming the Women's Tennis Association in 1973, a critical moment in the fight for equal opportunity within the sport.
In the same year, King threatened to boycott the U.S. Open if the winner of the women's singles title wasn't paid the same as their male counterpart.
She won, and so did Margaret Court -- the most decorated player ever in terms of singles titles -- to the tune of $25,000.
And despite having battled for nearly half a decade for parity, King believes there is still too much emphasis placed on physical appearance in some tennis coverage.
She was angered by an article in the New York Times on the eve of Serena Williams' victory at Wimbledon back in July that discussed the 21-time major winner's body shape.
"That drove me crazy," she said. "So what? Stop evaluating us. I mean, she is probably the all-time great. So stop it. Talk about her accomplishments.
"Let's evaluate Tom Brady's body. I mean, did you see him in the combines [the NFL's preseason scouting and training program]?"
One of King's most memorable contributions in the fight for equality came with a match that was most definitely out of the ordinary.
She took up the challenge laid down by Riggs, a notorious self-publicist and former grand slam winner who made a fortune gambling on his own matches.
Their "Battle of the Sexes" clash offered $100,000 for the winner and attracted an international television audience of millions.
Riggs, retired and aged 55 at the time, had beaten Court prior to meeting King but was overcome in straight sets. King said she'd have set women back half a century had she not emerged triumphant.
"There was also a shift of perception," she said of her victory. "That's what you want for both men and women.
"What the women got out of when I beat Riggs was self-confidence and higher self-esteem. For the first time they were asking for a raise, for instance.
"And they were actually getting them, which is more important. I played Bobby in 1973. So everything around -- for what I was thinking was about social change.
"And women in 1973 could not even get a credit card on their own. They had to have co-signing by a male still -- in 1973. People don't realize that -- they've forgotten."
Many facets of the modern game are directly as a result of King's lobbying.
Yet there is still just one high-profile woman -- Amelie Mauresmo -- coaching at the top end of the men's game currently.
The Frenchwoman, a former world number one and two-time grand slam winner, has been Murray's mentor since June 2014.
The appointment attracted a barrage of headlines at the time, but Murray was adamant it was an easy choice when speaking to CNN: "It was about finding the right personality with the right experience to help me.
"And if it helps bring more female coaches into men's sport -- and women's sport -- that's a good thing. Because there's absolutely no reason why someone like Amelie can't help me."
King is a big supporter of Murray, not just in his decision to employ Mauresmo, but also in his balanced approach to tennis.
"I think it's great -- let's get with the times," she said. "I just think Andy Murray's been great -- I love him for that.
"When he tweets and when he does his social media, he talks about women's tennis and men's tennis. He doesn't just talk about himself or just men.
"So for that, I love Andy Murray. And I think having Mauresmo there, visibly be there, it just sends a very positive message that either men or women can coach.
"We all have brains. So that's what coaching is, brains."
King's commitment to equality remains undimmed as she enters her eighth decade on the planet.
So where does she think things stand currently?
"So far to go -- not even close," is her evaluation.
"When less than 20% of Congress are women, that's a real good indicator.
"No, we're not in great shape at all. When you read about history, it goes fast. But when you live it, it's extremely slow."
King's "Battle of the Sexes" clash with Riggs is set to be immortalized by Hollywood, with a film release slated for 2016.
Steve Carrell has been signed to play Riggs, but the role of King is yet to be cast.
"I just get so embarrassed with that kind of stuff, I don't know," King joked. "I think it'll be great. Because I think it's important for millennials to see it."