The treatment of VN vets by the civilian community during the 60's and 70's as noted by several above was atrocious. As the VN war drug on and opposition to the war increased treatment of the military by the civilian community also increased both verbally and in sometimes violent skirmishes. Most veterans felt proud of their service to their country in Vietnam, yet many also had some doubts about the war and their own actions in it. In fact, some veterans protested against the war once they returned to the United States.
Also true (my own experience), it got so bad during those years active military did NOT wear their uniforms while traveling commercially (planes, trains, busses, etc.). We were told to wear civilian clothing to and from military bases from home and change into uniforms after arriving on base/post. And, if every day duty was at a civilian location such as a Federal Building we typically wore civilian clothes except when on TDY to an actual military installation.
The treatment of the military during Viet Nam was shameful and must not ever be repeated. True, the war itself was not popular - even by many actually in the military - but during draft years if called the choices were either to go (be inducted or drafted or volunteer by service), or be a religious conscientious objector (often joined anyway to be in medical service), or go to Canada. People like Cassius Clay (Mohamed Ali) refused to go (saying it was against his new Muslim religion to be in military... ha ha) and were somehow admired. True bio's of him tell the true story of what a jerk he really was. On the other hand many celebrities went when called such as Elvis Presley and were appreciated (even though his tour of duty was Germany and not Viet Nam).
During the Vietnam War era, between 1964 and 1973, the U.S. military drafted 2.2 million American men out of an eligible pool of 27 million. Only 25% of draftees during the Viet Nam conflict ever actually went to Viet Nam. One of every 104 draftees from June, 1965, the beginning of the Vietnam buildup, to June, 1969, was killed in action. Figures made public by the Defense Department show that roughly 33 per cent of Americans killed in combat were draftees. About 1/3 of those who served during Viet Nam are still alive today.