Rant: I spent 20 minutes photographing a storefront that was already empty

I walked into the Westland mall in Kalamazoo two Saturdays ago and got all excited over a shoe store with the shelves still full, so I spent 20 minutes snapping pics through the glass before I noticed the dust on every single box and a sign taped to the door saying it closed in 2019. What tipped me off was a mall worker who stopped and said, "buddy, that window hasn't opened in four years." I had been treating a display as a live business the whole time instead of checking the door or asking anyone first. Now I look for the film of grime on the glass before I even pull out my phone. What's your tell that a shop in one of these places is long gone but still dressed up?