FM, its not within your prerogative to overlook military indiscipline. If you are not saluted (and mean you, the holder of a commission) you ought to do something about it, rather than shrug it off.
Those personnel who do not salute you might not share your ideals about salutation. You are setting a bad example by accepting indiscipline. I'm not suggesting that a charge sheet entry is the answer, but a timely reprimand usually suffices.