You know, perhaps the main thing that turned Republicans on Nixon was hearing the tapes of him ranting and sounding like a delusional, paranoid, angry, racist psycho
Unlikely, everyone in Washington was receiving those drunken late night Nixon rants for years. It was the most common way the power brokers of the GOP heard from Nixon while he was "on hiatus" from 1962-1968.
Much of the concern, from both parties and media members, was that people often agreed with him even if just to shut him up or said stuff. Pat Buchanan of all people admitted he regularly did this because he, of all people, couldn't stand just how racist and anti-semetic the "old man" could get and would try to get him onto another topic.
The LBJ tapes are similar. I can't remember the Senator or Governor or state now, but there's an infamous one where LBJ goes on like a ten minute long rant about some other country and how they're dicking him around instead of doing what he says, and then he pauses and goes "hmmm" and the guy on the other end suddenly realizes he's supposed to talk and says something about how it reminds him of those "damn Japs" and this sets LBJ off on another rant about Japan.