The evidence is quite solid that Martin Luther King, Jr. did cheat on his wife, but the claims that he engaged in orgies or that he had sex with prostitutes, white or otherwise, appear to be totally undocumented at best and complete bunk at worst. Ralph Abernathy, a close personal friend of Martin Luther King, Jr. and King's successor as head of the Southern Christian Leadership Conference, wrote a tell-all memoir shortly before he died called And the Walls Came Tumbling Down, which was extremely controversial when it came out 1989, because of its discussion of King's infidelities. According to this page on snopes.com, which quotes extensively from Abernathy's autobiography, many African-American women found Dr. King extremely attractive, and King was not always successful in warding off extramarital temptation:
Martin and I were away more often than we were at home; and while this was no excuse for extramarital relations, it was a reason. Some men are better able to bear such deprivations than others, though all of us in SCLC headquarters had our weak moments. We all understood and believed in the biblical prohibition against sex outside of marriage. It was just that he had a particularly difficult time with that temptation.
In addition to his personal vulnerability, he was also a man who attracted women, even when he didn't intend to, and attracted them in droves. Part of his appeal was his predominant role in the black community and part of it was personal. During the last ten years of his life, Martin Luther King was the most important black man in America. That fact alone endowed him with an aura of power and greatness that women found very appealing. He was a hero — the greatest hero of his age — and women are always attracted to a hero.
But he also had a personal charm that ingratiated him with members of the opposite sex. He was always gracious and courteous to women, whether they were attractive to him or not. He had perfect manners. He was well educated. He was warm and friendly. He could make them laugh. He was good company, something that cannot always be said of heroes. These qualities made him even more attractive in close proximity than he was at a distance.
On the other hand, even though Abernathy risked a lot of ostracism from his peers after writing about Martin Luther King's infidelities, Abernathy never ever claimed that King engaged in orgies or that he had sex with white women, prostitutes or otherwise. The most likely reason that he never made claims like that is because those claims are untrue. Abernathy had no incentive to keep silent about tales of orgies or prostitutes, even if they had been true. Abernathy was close to death, in dire economic circumstances, and if Dr. King had involved himself with prostitutes and orgies, Abernathy would have probably included them in his autobiography in order to sell more copies of his book and pay off his debts. Instead, Abernathy wrote,
A recent biography has suggested without quite saying so that Martin had affairs with white women as well as black. Such a suggestion is without foundation. I can say with the greatest confidence that he was never attracted to white women and had nothing to do with them, despite the opportunities that may have presented themselves.
Another factor that burnishes Abernathy's credibility is that he claimed King had had a sexual encounter with a woman who was an African-American state senator from Kentucky. Since there was only one African-American woman in the Kentucky Senate at the time, we now know that woman was Georgia Davis Powers. Later on, Senator Powers published her own autobiography, I Shared the Dream: The Pride, Passion, and Politics of the First Black Woman Senator from Kentucky, in which she confirmed Abernathy's account that she had had a sexual relationship with Martin Luther King, Jr. In fact, in a later interview with a Kentucky newspaper, Davis said that she had gotten some pressure from some African-American male ministers in Louisville not to publish her book. In recollecting this backlash against her book, Davis said, "They thought somebody was going to tell on them. And the women just said, 'I wish it had been me.'"
His rampant adultery and serial, life-long womanizing revolted even some of his closest associates. Large parts of his doctoral dissertation were plagiarized. He had numerous ties with communists and Soviet sympathizers. Then-FBI Director J. Edgar Hoover knew this, which is why he considered King a “fraud.”
Moreover, King was a radical leftist. He promoted socialism, pacifism and the appeasement of totalitarian communism. He opposed the Vietnam War and even openly supported the Viet Cong and North Vietnam’s Marxist dictator Ho Chi Minh, praising them as anti-imperialists battling Western occupying powers. Yet, these Soviet-backed communists would eventually impose a murderous police state upon the Vietnamese.
At home, he called for heavy public spending, urban renewal and a cradle-to-grave nanny state. He was critical of the Great Society for not going far enough: White America’s collective racist sins could only be expiated through big-government liberalism. King called for racial quotas in government contracts, affirmative action and billions in welfare assistance. In short, he helped lay the groundwork for the modern Democratic Party - anti-war, favoring the redistribution of wealth and obsessed with identity politics.
King’s leftism ultimately betrayed his original civil rights creed. His call for a color-blind society was contradicted by his multicultural progressivism. Affirmative action, racial quotas, government handouts to minorities - these policies directly violate the basic principle of equality under the law. Contemporary Americans are not judged as individuals, but as members of a racial group, gender or ethnicity. This is a perverse inversion of the very kind of racialism prevalent in the Old South.
King’s socialism also convinced many blacks to adopt welfare liberalism. It transformed them into a permanent Democratic constituency. The results have been disastrous. The nanny state has crippled the black community, undermining self-reliance, entrepreneurship and personal responsibility. It has fostered family breakdown, soaring rates of illegitimacy and trapped millions in a cycle of poverty and urban squalor. King showed blacks the way out from segregation, but he led them to an economic plantation.