I was at a restaurant was giving free meals on Veterans Day. A guy was dressed in full uniform even though he was clearly too old.
More power to him if he can get in it.
Partial uniform items like fatigue shirts even devoid of rank and squadron patches, were banned from on base facilities. Off base partial uniform items were forbidden period. One exception was footwear.
I find it hard to believe now, that any branch of the military would allow, much less encourage, wearing uniform items out of context.
Considering anyone can buy anything online my first thought when I see someone in public wearing a uniform is grooming standards. The guy in this story wouldn't pass that test.
The next thing I look for is patches and awards and decorations. Anyone in a combat uniform wearing medals (particularly miniatures) is almost a dead give away as a poser. Usually, they also have four or five rows too, all in the wrong order.
The final consideration is age. A young or old person wearing they wrong type of uniform also screams poser.