Still thought I'd suggest it, did not see any thing on forums suggesting the usefulness of having sunglasses besides the look factor. But sunglasses actually being useful and change how you see the game to give you a +1 on others without them would be nice to see.
I would really like this, it could also give more use to other items with tint like motor cycle helmets. I also really hope they make headgear immersive like I talked about in my headgear thread. It would be really cool to put on sunglasses to protect from the glare and to be able to actually see the sunglases on the screen, if you have played the Project Nevada mod for New Vegas or the Misery mod for Stalker COP you know what I am talking about.
I love The Walking Dead, and I think adding a pair of shades like the ones Carl wears in the comics would be absolutely amazing! I believe it'd be a cool little easter egg for us fans. I'd be one of the happiest men on the planet if this was added. Surely it can't be too difficult to implement, hell, send out a black sunglasses template for Unity and I'll make them myself. They could be called broken shades, or half-covered sunglasses.