One of my rules is, “Smoking only permitted outdoors.” When I give the house tour, if the guest smells like a smoker I show him/her the outdoor table, give them an ashtray and tell them that they are welcome to smoke outdoors with the back door closed so the smoke doesn’t drift into the house. Bear in mind that I am in Southern California where the weather permits you to be outdoors almost 365 days a year at any time of day. If guests ask if it’s okay to smoke marijuana I tell them that I don’t care what they smoke as it’s going in their lungs, not mine.
While it’s true that cigarette smokes clings more than marijuana smoke, I believe there will be the faint smell of marijuana which to me smells like a skunk died several days ago. Also, bong water is one of the worst smells I’ve ever smelled and bongs get knocked over all the time.