I have been cruising for almost 20 years on various cruise lines and can honestly say I have never smelt stale smoke in cabins. The cabins have air conditioning and are cleaned after each use, you should be OK. Enjoy your cruise.
Understand that P & O have a no smoking in cabins (except on balcony) now. However have also been cruising for many years and have had cabins smelling of stale smoke - the last being on Aurora New Year Cruise - which was very bad. However I discovered that on complaining to customer relations they de-sanitised the cabin straight away changing all soft furnishings etc.
Could not have had better service. Sure we must have just been unlucky as friends travelling with us have always been ok. I'm sure you will enjoy Aurora. Carole
You can still smoke in your cabin on Aurora and Oriana and in 1 public room and on deck. Ventura and Oceana you can smoke in a balcony cabin and on deck.