Nixon had the balls to invade Cambodia and bomb Hanoi. Yup. Put that together with his defense of Chambers, and the outing of close Graham friend Hiss, and one gains a good amount of insight into the Lefts desire to destroy, and demonize him.
The Kennedys and the liberals hated him. They would do anything (and they did) to demonize the man.
I think his hatred and distrust of J. Edgar Hoover had a lot to do with his downfall as well.