Never worn a uniform in any sim (or a hat in any airline... I've somehow luckily managed to dodge that one) and I also do a lot of empty aircraft positioning / ferry-flight sectors and those too are always flown in civvies. I only ever wear the uniform when pax are onboard... though it's not as if the pax even see me, i.e. flight deck visits were long since banned, pilots walking about in the cabin is frowned upon and, if / when I decide to go for a crap, a curtain is drawn so the pax can't see the flight-deck door being opened and me going in or out of the thunder closet... indeed I could be sitting in the flight-deck in the buff (all be that not a pretty sight, wherein my svelte years are long behind me) and the pax would be none the wiser... uhm, thinking of that, I do know a bloke whom has 4 stripes (in the style of epaulets) tattooed on each shoulder but that's another story.