Having been of prime draft age at the time, all I can say is that few actually wanted to serve in Vietnam. It's why there was a draft. The War was tremendously unpopular. There were a variety of legitimate ways whereby it could be avoided. Staying in school, being deferred, a la Clinton, and myself. Being granted a medical deferment, like Dean- lots of seemingly healthy guys were deemed 1Y for flat feet, heart murmurs, back trouble, whatever the military docs decided. Guys who tried to enlist were turned away, deferred, for seemingly trivial medical reasons. Some guys went to jail, a very few obtained conscientious objector status, some guys just got drafted... even running off to Canada took a certain amount of conviction and nerve.
And then there was the Guard, and the Reserves. Everybody knew it took heavy connections to get into either one. Just the way it was, just the truth. Dubya's family had those connections, obviously, and more. Generally speaking, however, Guard commanders made their charges live up to their obligations or end up in the stinking jungle.
The simple fact that Dubya's record is, uhh, incomplete, and that he does nothing constructive to clear his name indicates that he may well have been granted extremely favorable treatment, even for a richkid guardsman.
And it becomes an issue when he parades around in military garb, staging carrier landings, claiming he served himself as he sends young troops off into harm's way. It seems hypocritical and deceptive, insulting to those who truly did serve.
I personally don't have a problem with anybody's role during that period of time, just so long as they're honest about it. Kerry and McCain deserve their accolades, they earned them. Clinton never laid claim to any, neither does Dean. None of them are lying about it.