I'm with Harvey.
If I play a smoking club (and I do) my breathing (and therefore my singing) suffers, when I get home my clothes stink like crap, and the next day I spend half my time coughing like some broken-down tinker's mare. And I'm neither a bronchitis sufferer nor an asthmatic, so it goes to prove what a filthy, antisocial addiction smoking is.
There are many other top-name artists as well as Harvey who only play at non-smoking venues, and their attendances don't seem to suffer.
If these guys who smoke want to poison themselves, fine. Just don't poison me.