I believe the reason Reagan and both Bushes returned salutes was that they appreciated what the gesture meant and the men who were giving them the salutes. Clinton and Obama don't care and never will care so they were and are half-assed about it. I wouldn't get eaten up over it because service members have other ways to understand the Clintons and Obamas don't give two figs for us, our traditions, or the Constitution we have sworn to protect.