Where There's Smoke ...
Miley Cyrus isn't Liam Hemsworth's only bad habit -- hours after news broke about the couple's engagement, the actor surfaced on a movie set ... lighting up a filthy cancer stick.
Liam chipped away at his life span during a quick break in New Orleans -- where he's currently filming "Empire State" -- and he wasn't eager to talk engagement.
The story broke today ... Liam and Miley are getting hitched after dating for three years.
Surgeon general's warning: sign a pre-nup.