The story about John Wayne being booed by wounded Marines is true.
William Manchester was a Marine who served in World War II and later wrote a memoir of his service called "GoodbyeDarkness". The following is an excerpt from an essay that appeared in The New York Times Magazine June 14, 1987. This comes from the web site http://a-mountain.com/?p=381
This is the excerpt:
“Once we polled a rifle company, asking each man why he had joined the Marines. A majority cited ‘To the Shores of Tripoli,’ a marshmallow of a movie starring John Payne, Randolph Scott and Maureen O’Hara. Throughout the film the uniform of the day was dress blues; requests for liberty were always granted. The implication was that combat would be a lark, and when you returned, spangled with decorations, a Navy nurse like Maureen O’Hara would be waiting in your sack. It was peacetime again when John Wayne appeared on the silver screen as Sergeant Stryker in ‘Sands of Iwo Jima,’ but that film underscores the point; I went to see it with another ex-Marine, and we were asked to leave the theater because we couldn’t stop laughing.
“After my evacuation from Okinawa, I had the enormous pleasure of seeing Wayne humiliated in person at Aiea Heights Naval Hospital in Hawaii. Only the most gravely wounded, the litter cases, were sent there. The hospital was packed, the halls lined with beds. Between Iwo Jima and Okinawa, the Marine Corps was being bled white.
“Each evening, Navy corpsmen would carry litters down to the hospital theater so the men could watch a movie. One night they had a surprise for us. Before the film the curtains parted and out stepped John Wayne, wearing a cowboy outfit – 10-gallon hat, bandanna, checkered shirt, two pistols, chaps, boots and spurs. He grinned his aw-shucks grin, passed a hand over his face and said, ‘Hi ya, guys!’ He was greeted by a stony silence. Then somebody booed. Suddenly everyone was booing.
“This man was a symbol of the fake machismo we had come to hate, and we weren’t going to listen to him. He tried and tried to make himself heard, but we drowned him out, and eventually he quit and left. If you liked ‘Sands of Iwo Jima,’ I suggest you be careful. Don’t tell it to the Marines.”