I've heard this about Alger Hiss being the reason why people hated McCarthy and later, Nixon, but I guess I have no concept of why this would leave the leftists in such a foaming state of mind. Was Hiss like a movie star at the time? What about Hiss was so great that liberals would spend DECADES defending him, and trying to destroy people who were "mean" to him?
If you want some good info re McCarthy, you should read Ann Coulter's book "Treason". That should clear things up for you.