To me, the act itself makes sense ICly. There are windows, puddles in the storm, ambient mirrors in places, even a whiskey glass can reflect your image back at you in the right light. I personally don't think it should require a mirror to check my disguise. Yet, I do feel there should be some risk to using glance this way.
So for starters, why not just make it a potentially compromising action when used to glance at yourself? Make glance a deleterious action to your disguise (if it isn't already). Seems like a simple fix.
But it could be taken even further. All those ambient objects that could be used to glance at yourself offer imperfect reflections. Imperfect reflections should sometimes yield imperfect results.
Ex. Joe Baka is slipping off of some gang turf after mugging someone, and he hasn't paid his dues. Shroud on, he is well disguised at the moment. Then he glances at himself. It's storming hard and he sees his reflection at his feet, checking his disguise in a well lit pool of water on the ground. All good, nothing to see here, he says to himself - just another shroud looking back at me. Except the image is blurred, and what he thinks he sees is a trick of the light, or maybe he's just so overconfident he doesn't see what might be obvious in a more perfect reflection. His disguise is compromised and he doesn't even realize it. He strides along confidently, only to be drug from his feet from behind, machete hovering over his face. The Art looks down at him, sneering. "You were warned about dodging tolls."
So yeah, look at yourself with glance all you want, but it's going to be a risk every time, either working against the integrity of your disguise and/or convincing you that you're better than you are...until it comes back to bite you in the ass.
