I would say I'm a pretty good-looking guy, but I can't smile well even if my life depended on it. I never show teeth whatsoever because I look half-retarded when I do, and I look like a creepy pedophile when I smile without showing teeth.
Can you smile well?
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I can't smile properly. Not even my natural smile looks good, so I use body language and my eyebrows to show I'm interested, "happy" etc.