When Mercedes Carrera took a uniformed Army sergeant to the 2016 Adult Video News Awards, it wasn’t a publicity stunt. After all, Carrera’s success as an actress hardly hinges on her reputation as a humanitarian. So when the 33-year-old porn star — whose portfolio includes roles in such films as “Nutz About Butts” and “All About Ass 2” — appeared alongside Sgt. Anthony Berg, a happily married Army reservist and Iraq War veteran, on the red carpet for the AVN Awards in Las Vegas, some were quick to call her motives into question. But Carrera’s support for the military is sincere. The daughter of a Vietnam veteran, she’s well aware of the difficulties service members face when they return home from war. She also knows that many of her fans wear or have worn the uniform.