hello @Gary545 and welcome to ABB CC.
In your listing you are very specific about not smoking, and the number of people permitted.
You need to message your Guests and advise them to nip it in the bud as they are in breach of Terms of Service.
You may also have a stench to try rid prior to your next Guests who may be looking forward to staying in a home free from such lingering smells. We all know those smells, including from Vapes and other Imitation Tobacco related products goes into everything.
With the recent and ongoing Cases related to Juul, it's perhaps timely you, and others, stipulated in your listing, if you so desire, No Vaping, E-cigarettes as you may find those who use them will try claim they are "Not Smoking".
All the best and I hope you are able to resolve this smoothly without any negative confrontation from the Guest/s
Make sure you write a straight-up truthful and accurate Review so others know in advance of potential issues arising.