Not quite the same, I think, McG — smokers voluntarily embrace the habit, and these days I note that the more amenable among them who are unable to give up [which most claim to wish to do, & to be about to do in the new year, &c] take pains to go out into the garden or otherwise not to force their habit on to the rest of us. G.g's song appears to be aimed at the exceptions to this.

Nonetheless I concur with you in finding it a provocative, disagreeable, and altogether somewhat disobliging song. "Scum" is indeed an unnecessarily strong and offensive term in the context.