Maybe it's a generational or geographical thing within our country? Because I'm also Australian and I've never heard "lush" used in conversation around me, with this meaning.
Although this thread has just explained a line from a song by a US artist that I've heard where "lush" is used in this context and it now makes more sense to me.
Although this thread has just explained a line from a song by a US artist that I've heard where "lush" is used in this context and it now makes more sense to me.