I think part (and, by no means, the only part!) of the issue the comic industry has with recruiting new blood is just getting people in the door. There are some legitimately great books out there, but if people don't go in comic shops to discover them, they're not likely to become comic fans. I'm working on a project now to look at basic accessibility (where comic shops are located relative to population centers) but it occurs to me that a store's outward appearance can also be a factor. Is anyone besides a die-hard comic fan going to enter a building if it looks pretty seedy from the street? Probably not.
Now, granted, a shop owner has less control of the environment surrounding a shop than s/he does inside it. The city might have a fire hydrant plopped just outside the entrance, or maybe a local beautification project has a tree planted in the perfect place to obscure the shop sign above the entrance. Maybe the stores on either side went out of business and those buildings have fallen into disrepair.
But the shop owner usually has pretty good control over things like the actual sign out front, the window display, sometimes the building itself. I think those things that CAN be controlled should be considered every bit as much as where a stack of long boxes go inside the store.
On a whim, I went through Google and pulled up the locations of a bunch of comic shops. Many have a "street view" available where somebody from Google actually drove by and took pictures. While anything set back from the road doesn't really show up very well, I've collected below a number of these street views. These are what people would see as they're actually driving past the stores. Would you stop if you passed by these places? Would your spouse/significant other? Would your mom?
I haven't been to any of these stores, and I'm not about to pass judgement on any of them. I'm just saying that this is what most people see when they drive past.