Have a military fashion fetish. Love the Nazi SS uniforms the most (it's unfortunate about what their purpose was, because their uniforms were so awesome looking)
Russian uniforms I like as well.
American ones I'm not as into except for maybe marines (like the jacket with the red trim)
Some things that are offensive to people are the nazi symbol and yes, wearing medals that you did not earn. There will always be the few who get offended when you wear military fashion.
Going to goth clubs and being dressed up, I've had people in the military come up to me and say- "You're an idiot for dressing that way and I think you're dumb and dumb looking!" (paraphrasing) so I respond by saying: (and this is my response- I am not trying to start an argument or debate here, just merely stating how I respond) "I don't think you're very bright yourself signing up for the military and fighting/dying for a country that doesn't care about you"
So really, what I'm saying is, if you are going to dress military, then be ready to have people come up to you and let their opinions be heard. That doesn't mean you can't shoot back with your own opinion.