"Didn't Carter benefit from the Watergate scandal, even if Ford had nothing to do with it?"

Nah, the media was very successful at painting Ford as boring. It was an unfair characterization- unless boring equals lack of scandalous material. In this definition of boring, Kerry should be a fresh and exciting face.

Now, it did affect the campaign spin- Carter was spun as an "Outsider". Which is of course, is almost as silly as calling Kerry a "Outsider".
For Republicans an "Outsider" is a businessman or even a movie star. For Dems an "Outsider" is someone to be kept in the dark, which is shoveled bullshit- a "Mushroom" would be a more descriptive term.