In one picture Dominic is in Vietnam sitting around with some soldiers smoking and drinking, on his left arm is a tattoo, and on another photo when Dominic is home in USA he has the same tattoo on his left arm, i dont think he faked that.
Ya its not a question of wheather or not he actually was in vietnam, people are questioning if he was really in the special forces like he claimed, i wouldnt be surprised if he was lying about. In all the docs that hes in(and hes in a lot of them) he seems to like to take a lot of liberties with truth especially with the extent of his involvement with the demeo crew. Plus you can never really trust an addict.