I think, while it may seem to look cool, putting a smoked lens on the taillight of a motorcycle is a bad idea. First off, it's not legal in many states. For example, in Alaska, the taillight must be visible from a distance of 1000 feet at night. Smoked lenses rarely meet that requirement. Secondly, we were invisible enough as it is, why would you want to make the problem worse by reducing the amount of light from the bike?
I understand that it may not be an issue if you never ride at night, but still, you want as much light as possible to the rear. Besides, your taillight assembly houses both the rear running light and brake light. You'd want them to be as bright as possible. Putting on a smoked lens is a safety issue, IMO.
"Don't sweat the small stuff---it's all small stuff"
'09 650 VStrom