Motives and incentives are important in weighing stories. The ["Swift Boat Veterans"] knew this ad would subject them to intense fire. They don't seem to be desperate losers. Assume they're Republicans and really hate Kerry for what he did after the war. Can this really explain what they're doing to themselves by participating in what they had to know would be exposed as a blatant lie, if it is indeed untrue?
Memory is a tricky enough thing when not under stress; just try the notorious "a gorilla walks into the room…" experiment. Add the fog of war on top of it, and that's explanation enough. I don't even have to characterize the SBVs as "liars" or even just partisan dupes to reach this conclusion.
More important, though, is the unique effect of adverse engagement outcomes (if nothing else, the military can come up with some startling euphemisms for "losing"—that's actually a recommended 1960s term for after-action reports) on memory of the fight. People don't want to believe that they're being shot at for no reason; they don't want to believe that their friends and colleagues were killed or wounded in their presence for no reason; they don't want to believe that any reason was less than personal. I served with too many veterans, and monitored too much myself, to have many illusions about this. Combine the need for an acceptable reason with incomplete information, speed, and general stress, and one should be able to accept radically different views of the same harrowing incident as incomplete, even incorrect, but nonetheless true within the reference frame of someone recalling that incident. Add in thirty years of festering memories, personal tragedy, Monday-morning quarterbacking, and I cannot blame the SBVs for anything they said.
I cannot say the same about their current "handlers," however. The means through which the SBVs' "stories" were initially presented and continue to be defended (however ineptly) were contrived by a particularly reprehensible type of individual(s): Those with no serious military service, extreme partisan positions, and deep distrust of and disrespect for military members who aren't flag officers. During my time in the military, and particularly in DC, I saw a helluva lot of these scum. (They're not exclusively in one party, either.) I have nothing but contempt for them. If the SBVs honestly believe what they're saying, they can make their information known to the relevant service IG. Even "Title 10 Mother!%&*!ers" will at least investigate the allegations if they have even a shred of credibility to them.