A muckraker is, primarily, a reporter or writer who investigates and publishes truthful reports involving a host of social issues, broadly including crime and corruption and often involving elected officials, political leaders and influential members of business and industry. The term is closely associated with a number of important writers who emerged in the 1890s through the 1930s, a period roughly concurrent with the Progressive Era in the United States.
Muckraker is NOT a pejorative term. It is actually a good thing...............