Setzer with his BC face on
That expression is a little hard to read. I would recommend lightening your shading a bit, and darkening the outlines/features. Your OC is normally seen with just the moustache, not also the sunglasses, yes?
Some kind of eyewear. I've been tweaking a bit and making a few different accessories for him.
Hmmm, well. It might be easier to pick either moustache or eyewear, because those each obscure a particular feature on the face. It makes it harder to read the emote's expressions if both the eyes and mouth are partially obscured.
His mustache would be his mouth substitute, kind of like Yosemite Sam from Looney Tunes. I'll have to do an expression sheet meme for him later. The sunglasses wouldn't be something for him all the time since he's near-sighted...