The vitriol has been mostly one-way, but the enmity between David Haye and Wladimir Klitschko, and Klitschko's brother, Vitali, runs in both directions.
Time for David Haye's fists to do the talking
The British heavyweight champion's grandest gesture of denigration, however, will come tonight when the bell sounds to signal the end of his unification fight in Hamburg.
The only question is who will be the subject of his final act of slighting: Klitschko or the boxing public? Win or lose, Haye will struggle to duck or weave past expectations cast upon him by the sport's traditionalists.
He will be expected to show a rare glimmer of grace. He will be expected to embrace his nemesis. And he will be expected to speak of his opponent's strengths and spirited character.
If he refuses to enrol in this ethical square dance and instead maintains an aggressive, contemptuous approach towards his opponent, he will be criticised and castigated by pundits and boxing insiders, people who will say dark things about Haye long after the names he called Klitschko are forgotten.
Yet if he conforms to historical convention, his three years of mudslinging and trash-talking will be revealed as nothing but hot air, a series of lies generated to convince the public his motivation is not money but rather a desire to pulverise a man he loathes.
It is a contest Haye can hardly win.
Still, pre-fight posturing is as much a part of pugilism as perspiration. Muhammad Ali grabbed the sport by its vein-bulging neck in the early 1960s when he arrived on the scene as an Olympic gold-medallist who cockily recited rhymes predicting the round in which he would knock out his opponent.
One such quintessential couplet delivered ahead of his 1964 title fight detailed: "Here I predict Sonny Liston's dismemberment / I'll hit him so hard, he'll forget where October-November went." As great as Ali was, and he remains widely regarded as the greatest boxer of all time, much of his charm was built on the commotion and feverishness he was capable of creating through his pre-fight posturing.
In a television interview he said that he took the idea of trash-talking from George Wagner, an American professional wrestler whom people loved to hate.
"I got this from Gorgeous George," Ali said. "I saw him doing it and thought, this is a good idea, he is getting rich. So I started talking, 'I am the greatest, I cannot be beat, I'm too pretty to be a fighter' …"
Building hype around themselves continued to be a marketing ploy implemented by boxers throughout the 20th century. But it was not until the arrival of "Iron" Mike Tyson, the intimidating American, that trash-talking truly landed in the gutter.
Here was a man who opted not for stanzas of sardonic poetry, but instead simply spoke straight of his savage intentions.
When, in 2002, he sounded out British boxer Lennox Lewis for a future fight, he announced he was "the best ever".
But he did not stop there, adding: "There's never been anyone as ruthless as me. I'm Sonny Liston. I'm Jack Dempsey. I'm from their cloth. There is no one who can match me. My style is impetuous, my defence is impregnable and I'm just ferocious.
"I want his heart. I want to eat his children."
Unlike Tyson, Lewis refused to bite. Instead, the powerful Englishman did his talking in the ring, where he reduced the menacing figure of Tyson to a moveable punching bag before flooring him in the eighth round.
Lewis's trainer that day was the American, Emanuel Steward, a venerated figure in the sport. Tonight, Steward, now 66, will be in Klitschko's corner. He is understandably unmoved by Haye's blatant braggadocio.
"Haye thinks we're worried about him? That is a joke," Steward said.
"I have never seen Wladimir in such a great state of mind. I feel the same way I did before Lennox's fight with Tyson, or Tommy Hearns before his fight with Roberto Duran. And when I feel this good, everything's OK."
Much of the Haye-inspired hype surrounding tonight's fight at the Imtech Arena is the product of the 30-year-old Londoner's immense confidence mixed with his distinct lack of respect for either his opponent or any sort of moral code.
This week he cited the E. coli virus that has killed 48 people in Germany as being "more dangerous" than Klitschko. In 2009, he wore a T-shirt to a news conference in Germany with an artist's rendering of Haye holding up the heads of Klitschko and his brother, Vitali, who is also a boxer.
On Thursday, Haye posted on his Twitter account a link to a crass, mock-subtitled video featuring an actor playing Adolf Hitler apparently discussing the imminent demise of Wladimir and Vitali at the hands of England's "Haye-maker".
With both brothers based in Hamburg and the fight taking place in the city, a video igniting memories of Germany's Nazi past is as bad-taste as it gets, and the British Boxing Board of Control revealed that they have warned the WBA champion about his conduct.
The insults have lost Haye many fans, several of whom are disgusted by the manner in which he has treated the reigning WBO and IBF champion. Klitschko even claims that when he was in London recently, the majority of people who approached him said they wanted him to beat Haye.
Yet while the Ukrainian merely dismissed Haye's insults as "trash … disgraceful and disrespectful", his trainer acknowledged that the Briton's cocksure display of confidence means he is proving to be an altogether different proposition to previous opponents.
Klitschko has not faced a fighter with such high belief in his abilities since he was knocked down three times in 2005 by the Nigerian Samuel Peter before recovering to win on points.
"Haye brings to the ring speed, power and the mind set of a winner," Steward said.
"He's confident, and that's something Wladimir hasn't experienced since his first fight with Sam Peter. There's a whole new energy that Haye brings that Wladimir has not had to deal with since then."
With both boxers intimating that the trash talk has run its course, the next joust will be physical rather than verbal.
The three-year wait is over, the time for talking is complete and tonight, at least, actions speak louder than words.