I submit the following as evidence that they are only called "conspiracy theories" until proper light is shed on them and they are proven to be true. And so, "CT" is really shorthand for "That's crazy! I don't believe it!"
1. The Dreyfus Affair: In the late 1800s in France, Jewish artillery officer Alfred Dreyfus was wrongfully convicted of treason based on false government documents, and sentenced to life in prison. The French government did attempt to cover this up, but Dreyfus was eventually pardoned after the affair was made public (an act that is credited to writer Émile Zola).
2. The Mafia: This secret crime society was virtually unknown until the 1960s, when member Joe Valachi first revealed the society's secrets to law enforcement officials.
3. MK-ULTRA: In the 1950s to the 1970s, the CIA ran a mind-control project aimed at finding a "truth serum" to use on communist spies. Test subjects were given LSD and other drugs, often without consent, and some were tortured. At least one man, civilian biochemist Frank Olson, who was working for the government, died as a result of the experiments. The project was finally exposed after investigations by the Rockefeller Commission.
4. Operation Mockingbird: Also in the 1950s to '70s, the CIA paid a number of well-known domestic and foreign journalists (from big-name media outlets like Time, The Washington Post, The New York Times, CBS and others) to publish CIA propaganda. The CIA also reportedly funded at least one movie, the animated "Animal Farm," by George Orwell. The Church Committee finally exposed the activities in 1975.