How Smearing Started
Possibly with antagonism against President Carter and his energy policies?
One of Carter's areas of major legislative accomplishments was his comprehensive energy policy, and getting the Crude Oil Windfall Profits Tax passed to finance it. This made him some serious and wealthy enemies.
... who had operatives that schemed to ridicule him.
Dave Johnson recalls that before the Carter years, "This kind of mean-spirited, harsh, extreme, cruel, mocking, ridiculing partisan attack that we're so familiar with today was not something that the public had been exposed to on such a scale in the 1970's."
And if you scroll down to the bottom of this late 2002 blog archive:
John Kerry is running for President. Character assasination begins.
From Seeing The Forest.