I got mistaken for being a NASCAR driver once when wearing a TIE Fighter Pilot suit, so it is easy to get misidentified when wearing something that is near to what a citizen understands it to be.
This is an excellent topic. As a personal preference I have never and am not ever going to wear ribbons or medals with any costume I do.
I know of cases where an imposter was trying to act like a badass and when called out claimed he was just honoring the troops. I have had veterans misrepresent their service because they didn’t feel bad ass enough.
What we, and other military based fandoms, don’t do is claim anything we have done as actual service. I have seen fans wear military ribbons, a few I earned myself after 20 years in the Navy, and I asked about it and there was such an earnest desire to respect the source, and they were not trying to get a discount at Hooters.
Just don’t be a douche and say you are something you are not. I fully admitted to not being a NASCAR fan.