This is a topic that is like a bad habit....no pun intended....it goes away, them comes back. If you do a search, there are tons of threads on this.
From all i have gathered, all ships allow smoking, some times it's really bad, then sometimes it can't be smelled. One of those catch 22's. depending on how sensitive your nose is, balcony vs inside/windowless stateroom, what deck, how long the cruise is for, etc.
on those cases where you want to be sure, or at least help, bring a small can of Ozium. That stuff works wonders.