This is a good question and you'll find that there is a range of answers. My viewpoint is one that out of deference to military personel I would not wear the rank. It is a truth in advertising type of thing from my viewpoint, I would not want anyone to see it and think that I was something I wasn't. From the lowest private to the highest general, and ranks for all services, the rank is earned and there is sacrifice, if I have not done the earning or made the sacrafice I don not want anything to even suggest that I claim what is not mine. Re-enacting is different and in some circumstances you may do some things to honor say your dad or grandfather that is okay. But everyday stuff, for me i'd say no.