McCarthy is known for "witchhunts" only because he was a conservative.
In 1934, the McCormack/Dickstein committee went after conservatives by claiming those opposed to FDR were planning an armed "putsch" to undo the New Deal.
On Feb.11, 1941, Dickstein (D-NY) took to the floor of the House and declared:
One hundred and ten fascist organizations in the United States have had, and have now the key to the back door of the Un-American Activities Committee!
Dickstein, by the way, was a Soviet spy.
I also believe his soviet code name was "crook". Every-time the dissenters start one of their diatribes about McCarthy, and you come back at them I have a nice chuckle.
On the subject of Nixon besides the Hiss trial the lib/commies despised him for destroying the commie leaning Helen Douglas in one of his early campaigns in California. My red diaper baby neighbor still brings it up.