"Media coverage of Iran-Contra was pretty intense, right up to the moment when everyone realized that Reagan was responsible and could be facing impeachment. Two Republican presidents in a row leaving office in disgrace?!?!?! And especially 'Morning in America" St. Ronnie?!?!?! Not gonna happen. Media dialed it back, and then CIA director Casey copped to running the entire thing, only to expire 6 hours later from a hitherto undetected case of brain cancer. From there on out, the media made an unconscious decision that Democrats really needed to be put in the same place as Nixon and Reagan. Hence the never-ending in-depth coverage of anything and everything Republicans tried to make a scandal of: White House travel office, Rose Law firm, Whitewater, Vince Foster, Lincoln Bedroom.
"This extended to 2000 when Al Gore was called a liar for telling the truth, and Bush's obvious lies were spackled over as just the kind of things a guy you'd like to have a beer with might say. And it continues to this day. It has created this astounding double standard in American politics under which Republican politicians can commit actual crimes and suffer no consequences, while Democrats are hounded from office for even imaginary minor offenses."
-- Derelict, Lawyers, Guns, and Money, comments [thanks to realinterrobang for quoting this earlier]