Spray Tint - Bad Idea
There seems to be a lot of information swirling around about spray tint lately and I can tell you: don't do it. If you 're looking to black out your tail lights the best way to go about it is simply to use film. Otherwise you run the risk of ruin your lights for good.
Blackout with Paint
Blacking out your taillights with spray paints like VHT leave your car permanently disfigured and you only have the option of buying whole new tail lights if you mess up. Pleus sand your lights, spraying them, clear coating and polishing them back to a shiny finish is no job for an amateur.