@Sarah977I'm also a smoker (of cigarettes) and when I first listed on Airbnb, I had a housemate who smoked too, so I felt it was important to mention this. I didn't want guests complaining about it after they arrived.
It's also in my house rules that smoking is strictly NOT permitted in the guest bedrooms. I had a couple of guests break that rule early on, but no problems with that since then. There is a garden and roof terrace, so they can easily go outside for a cigarette.
You would think that the smoking allowed policy would put off non smoking guests, but it doesn't seem to, especially as most guests don't read anything, or not in detail anyway. So, by this policy not appearing in the summary of the house rules, many, many guests will miss it.
I always message guests asking them to confirm they have read the full listing and house rules, "paying particular attention to the points re the cats, smoking and check in/out times". So many guests will just reply, "we love cats and we are non-smokers", which to me is a dead giveaway that they haven't actually read the house rules at all (if they have, they would normally respond along the lines of "we are non-smokers, but we don't mind other people smoking") so it's quite useful in spotting the non-readers!
I've only had one problem so far, where a guest claimed in her review that it was never mentioned that she would be staying with a smoker and marked me down for accuracy and overall because of this issue alone. I messaged her to point out that it IS mentioned on the listing, again in the house rules and in two separate messages I sent to her which she had replied to. The saying "You can lead a horse to water, but you can't make it drink," springs to mind.