Read 'Stalin's secret agents: the subversion of Roosevelt's government' and 'Blacklisted by history' by M. Stanton Evans and realize how wrong you are. Mc Carthy was dead right on a great number of things. It wasn't him that harmed American interests.
A *very* anti-Communist historian on McCarthy:
"By the time McCarthy was making his allegations, however, the most significant Soviet espionage networks had been all but destroyed and/or neutralized thanks to defections, American counter-intelligence, the FBI’s full-court press against the CPUSA, and President Truman’s loyalty-security program for government employees. Still, McCarthy not only persisted, but sought to paint FDR’s New Deal and Truman’s Fair Deal as a disguised Communist plot, while depicting such prominent administration officials as Dean Acheson and George C. Marshall as participants in or dupes of a Communist conspiracy.
"To be sure, though it is often alleged that Wisconsin’s junior senator never uncovered a single Communist, McCarthy did identify a number of party members in the US government, including Annie Lee Moss, a civilian Army employee, who is discussed at some length in Evans’s book (and for good reason, as Moss is frequently cited as an example of McCarthy at his worst). But McCarthy did not establish his national standing by correctly identifying this low-level Army employee as a security risk. He made it, to quote McCarthy in a speech on George Marshall, by thundering in June 1951:
'How can we account for our present situation unless we believe that men high in this government are concerting to deliver us to disaster? This must be the product of a great conspiracy, a conspiracy on a scale so immense as to dwarf any previous such venture in the history of man. A conspiracy of infamy so black that, when it is finally exposed, its principals shall be forever deserving of the maledictions of all honest men. . . .'[3]
"Certainly, several US officials, including some very high ones in the Roosevelt and Truman administrations, displayed great naïveté toward Soviet espionage, and internal security policies until the late 1940s were notably weak. But there is no evidence to justify McCarthy’s allegation of wholesale administration or Democratic complicity in this treachery. Officials (like Alger Hiss) who spied or attempted to influence US policy on behalf of the Soviet Union, also betrayed Roosevelt, Truman, their administrations, and their colleagues, in addition to violating the nation as a whole.
"Normal democratic politics cannot proceed when one side regards and depicts the other as the enemy of fundamental values, and somehow illegitimate. Yet that is what McCarthy attempted to do, via demagoguery and malign partisan zeal. That he did not succeed, or even come close, hardly mitigates the fact that his role was an irretrievably negative one. It is true, and Stan Evans makes the case, that McCarthy was not a satanic monster who terrorized the nation and seriously threatened its democratic values. But he was a hindrance, rather than an asset, to a rational anti-Communist consensus, and is not deserving of the vindication that Evans seeks to confer."
http://www.washingtondecoded.com/site/2007/12/mccarthy-accord.html