US military (service flags, and general/flag officer flags) and the Stars and Stripes only. Everything else is primping.
Now, if you want to go so far as to bitch and moan about some guys and gals on the FOB who are holding out a flag of whatever type while somebody takes a photo of them, that's merely primping. And that kind of thing has its place when you're mugging for the camera.
But it's a different animal altogether when you string up that logo flag or college flag or even state flag on a flagpole and you INTEND for that flag to wave in an official capacity -- not good at all, IMHO.