Question

what is one reason soldiers were shunned when they returned from vietnam

Answer 1

One reason is that the war was very unpopular therefore soldiers were seen as representatives of the war.
As well as some people believed that the soldiers had acted unethically and irresponsibly.

Answer 2

Soldiers returning from Vietnam were shunned because the whole idea of the war was considered unfair.Going to a foreign country to take the lives of farmers and innocent women and children was considered , and it is still today, by many ,as irrational and even immoral.Soldiers were under orders to kill and pacifists tought that they did not deserve any respect or attention from American people.