Reddit reviews They Wouldn't Let us Win: Jackson County, Alabama, Veterans Relive the Vietnam War

They didn't spit on soldiers. That was an urban legend that war-hawks started repeating in the late 70's to push back against a public narrative which had developed as a result of widespread media coverage that the war was a morally bankrupt quagmire. Since then their entire generation has been reliving that movie in the first person. Zero printed reports of spitting occurring at the time exist, and very few printed reports claiming that it occurred exist after the war but before the premiere of that movie. You will surprisingly often hear quotes from the movie repeated verbatim, even by people who were actually deployed.

It was drummed up in the 2004 Presidential campaign to smear John Kerry, a war hero with regrets about our actions in Vietnam, by the campaign of George W Bush.