Still the same game in attack ads: associate the candidate with negative images (in this case, it's the smoking gun that could come in the form of a mushroom cloud -- wait, that wasn't all that long ago!). Word-association, no matter how meaningless, still works. As the SNL Palin rap phrased it: "When I say Obama, you say Ayers! Obama! Ayers! Obama! Ayers!" Or, if you're Joseph McCarthy Michele Bachmann: "Obama! Anti-American! Congress! Anti-American! Investigation! Anti-American! I never said Anti-American!" (See how that works?)
Full disclosure: The anti-Goldwater ad above, perhaps the most scandalous political ad in American TV history (sorry, "Willie Horton"!) actually ran only once. More about it here.