Well, maybe you have more info than I do. I just don’t recall reading or hearing about thousands of depraved priests slipping into the priesthood prior to Vatican II. I think in the 1960s, you had a perfect storm attack the Church—First the Vatican II conference which lowered standards, then the Sexual Revolution of the 1960s, the finally the rise of left wing Marxist Theology which infected the Church at about the same time. All of these came together to form a perfect storm which I think allowed so many depraved individuals to slip into the priesthood.
Let me add that the progressivists who hijacked Vatican II, were not born over night, they were laying low since Pius X scattered them.
Msgr. Eugenio Pacelli, before he became Pope Pius XII and while he was still serving as Vatican Secretary of State during the reign of Pope Pius XI (early 1930's), made an astonishing prophecy about a coming upheaval in the Church:
"I am worried by the Blessed Virgin's messages to Lucy of Fatima. This persistence of Mary about the dangers which menace the Church is a divine warning against the suicide of altering the Faith, in Her liturgy, Her theology and Her soul. … I hear all around me innovators who wish to dismantle the Sacred Chapel, destroy the universal flame of the Church, reject Her ornaments and make Her feel remorse for Her historical past".
Pope Pius XII's biographer, Msgr. Roche, noted that at this moment in the conversation, according to a Count Galeazzi, “the gaze of the Pope, seen through the lenses of his glasses, became supernatural, and there emanated from his tall and slender body an irresistible mystical force.” Pius XII then said (in answer to an objection from a curial Cardinal):
"A day will come when the civilized world will deny its God, when the Church will doubt as Peter doubted. She will be tempted to believe that man has become God. In our churches, Christians will search in vain for the red lamp where God awaits them. Like Mary Magdalene, weeping before the empty tomb, they will ask, “Where have they taken Him?”29
Long before Vatican II, the progressivist innovators were preparing themselves for the day when they could unleash their cesspool of novelties long before. Vatican II was their stage opening. The rest is history now, 50 years later.