Well you must have missed the primarily on the ramp part of my post. The ramp is considered an "optional salute zone" ... primarily because you are not required to wear your cover there (as many of us are working in our perspective shops and on vehicles) ... so you don't absolutely have to salute. Outside of that, those Marines that gaffed off the salute probably have done a couple tours in Iraq...having primary respect for their Marine officers. YES they should show the proper resect, and by and large they do. But you can't say they are shvtbags just because they've got pride and a little attitude. If it'd been a Marine officer walking by they'd have snapped to.
Regardless, being a Mid you don't get much experience with enlisted troops.. I'd recommend witholding judgement. Thats not to say they shouldn't be corrected, just that they are definitely NOT shvtbags. You can't measure someone's conduct by that... the E-4s and below are hard workers. Now if they'd gaffed off a Marine officer that'd be something to get up in arms about. So, they should have saluted, but they're still probably good Marines. It sounds like the situation was corrected anyway.
/rant