Yes, we need to hear from Sugar!
You can teach him to smile, you know. I taught Ninja to smile and he'd do it any time he thought he was in trouble. When I'd come home from work and he met me at the door, smiling, I knew he'd done something wrong. Sometimes I never found it, so I think he was just THINKING about doing something wrong. In any case, he always told on himself, LOL!
If you want to teach him, I'll tell you how I did it. I'd pull his lips up and say "SMILE!" and then give him a treat. He was confused at first, but one day the light bulb went off over his head and the brain cells fired in unison, and he got it. After that, if I said "Smile!" (or if he did anything wrong) he'd smile, nice and big. Used to scare the crap out of visitors. If he thought they were afraid of him or didn't like him, he'd get right in their face and smile, hoping to get a treat, or at least a "good boy."
I didn't teach any of my others to smile just because of how frightened it made some people who didn't know him, so there is that to consider. But it's an easy trick, and I'm sure Sugar would get it.