muckraker

A person who habitually muckrakes.

One who investigates and exposes issues of corruption that often violate widely held values; e.g. one who exposes political corruption or the poor conditions in prisons.

A sensationalist, scandal-mongering journalist, one who is not driven by any social principles.

One of a group of American investigative reporters, novelists and critics of the Progressive Era (the 1890s to the 1920s)

one who spreads real or alleged scandal about another (usually for political advantage)