Are service members and or veterans portrayed poorly in television and movies?

Service members and veterans are portrayed by actors in accordance with the script and the director's wishes.

No more, no less.

Even movies people love because they're supposedly "historically accurate" are following the whims of the script writers and the director.

Sometimes service members and veterans are portrayed accurately and well, other times less so.

People who want to know how things "really are" need to put the research time in to discover where the line dividing reality and fantasy/entertainment lies.

The problem is that the people who make the movies have no real understanding of what soldiers are and how they interact. You'll either get the ultra progressive assumption that all soldiers are callous unthinking robots who only live to kill, or you get the ultra conservative perception of us being stoic heroes who only make choices to benefit the country. Oddly enough the comedies involving the military are really the closest be even those are exaggerations of how we act. The film industry plays to their audience, which either sees us as villains or god like heroes. It's understandable most Americans have never served and it's hard to explain military life to the uninitiated, so they just don't. This leads to a great divide in our society approaching a caste system.

In some cases perhaps. Most of what I see is a glorification more than anything else.