The US and the West faced for 45 years a totalitarian system that had conquered a dozen neighboring countries and had a powerful military. How far was "too far" in combating that?
As mentioned, there were Communist spies in the US government, far more than was generally understood at the time; we know that now thanks to the Venona files. That doesn't change the fact that Joe McCarthy was almost always correct only by accident. (You shoot in a random direction often enough, you'll hit someone eventually.) Worse, his excessive rhetoric likely for years discouraged legitimate rooting out of said spies.
As mentioned, there were Communist spies in the US government, far more than was generally understood at the time; we know that now thanks to the Venona files. That doesn't change the fact that Joe McCarthy was almost always correct only by accident. (You shoot in a random direction often enough, you'll hit someone eventually.) Worse, his excessive rhetoric likely for years discouraged legitimate rooting out of said spies.