An interesting change in etiquette that has occurred over the last couple of decades ~~
Although I am a *very* ex-smoker [my last smoke was on 3 April 1975], I have never thought it hospitable to prevent guests smoking in my home. The smell goes within 12 or so hours, I find. Nevertheless, over recent years, my few smoking guests have just gone instinctively into the back garden to smoke. I have said that I don't insist on it, but they always say that they would think it discourteous to smoke in the house, and wouldn't feel comfortable doing so.

~M~