Somebody really needs to invent a dressing booth for photographers. I'm surprised, in this selfie-obsessed age, that this hasn't already been done. I know I'm not the only person who takes selfies in fitting rooms (and not just for perverted reasons, either - how are you gonna remember or show your friends how you looked in that dress?), because I've seen them on the internet!
I'd like a booth with decent lighting, enough space to take full-body shots (without tilting your phone), and a mirror wide enough not to have awkward angled borders along the edges that you can never crop to your satisfaction. And if we're taking the time to design it right, we might as well make it so that there's enough space to hang up clothes, somewhere that doesn't end up creating bulky clutter in the background of your shots. A trick or two with angles and positioning could be enough to accomplish this. If a store wanted to go the extra mile, they could even install some kind of phone mount on which you could hang your phone, in a position convenient for snapping photos (or even video) as you twirl in front of the mirror in each of your prospective outfits. Am I crazy, or does some or all of this sound like a great idea?
You'd have to make a point to keep the mirrors clean, also - which could be a huge job. At the very least, you could provide mirror wipes in each booth, and a small trash can for discarding (applying the same technique for hanging hooks to keep it out of view of the mirror) - like they do for wiping the handles of buggies down at the supermarket. Then, those who are truly serious about their fitting room pictures could take the extra time to clean the mirror, and those who aren't can simply ignore it.