I have very little knowledge of this beyond second hand stuff told to me by my folks. I am still a wee baby compared to some of you seasoned veterans here at the 'Cat! ;DMy perception of it pre-fall of the USSR was that it was mostly a witch hunt.
Since other evidence has come to light since that time, I can only say that, regardless of there having been a reality behind the suspicions, the tactics were wrong...period. Walking all over peoples rights, regardless of there being a threat or no, leaves us all open for a dictator to step in and take all of our rights away "for our own good". Isn't that the exact issue that the US had with communism to begin with? So, how was what McCarthy did any better?
However, I will say this: Evil most often does not *know* it is evil. People mainly do what they do because they believe it to be what is good, right, and best.