“Had observers known in the 1950s what they have learned since the 1970s, when the Freedom of Information Act opened the Bureau’s files, ‘McCarthyism’ would probably be called ‘Hooverism.'” History professor Ellen Schrecker
During J. Edgar Hoover’s long tenure as Director, the FBI was very successful at spying on organizations hostile to the interests of the United States, including the Ku Klux Klan and the Nazi and Communist parties. Hoover is demonized in mainstream history books because the left wing activists who write most of the textbooks resent his efforts against one of those three organizations.
For some unknown reason, College professors and other left wing extremists tend to be anti-anti-Communists, implacably hostile to anyone who ever fought against Communism in any capacity. That being the case, J. Edgar Hoover would get much more sympathetic treatment in the history books if he had restricted his anti-subversive efforts to the KKK and the Nazis.