A lot of this information is at least a year old:
Almost all cruise lines no longer allow smoking inside of the cabins. So walking into a "smelly cabin" is not an issue.
Here are the current smoking policies on the major cruise lines:
Smoking (including cigars) will be permitted in designated exterior open deck areas (starboard side) of all our ships. Additionally, smoking will also be allowed in the jazz clubs of the following ships: Carnival Destiny, Carnival Triumph, Carnival Victory, Carnival Spirit, Carnival Pride, Carnival Legend, Carnival Miracle, Carnival Conquest, Carnival Glory, Carnival Valor, Carnival Liberty, Carnival Freedom, and Carnival Splendor.
* All Spa Suites and Staterooms, inclusive of the balconies, are an entirely smoke-free environment. Spa suites and staterooms are on the following ships only: Carnival Splendor, Carnival Dream, Carnival Breeze and Carnival Sunshine.
* Effective December 1, 2011, smoking will be prohibited in all guest staterooms. Guests in balcony staterooms may smoke (including cigars) outside on their balcony.
Guests who smoke in their staterooms will be assessed a $250 USD cleaning and refreshing fee on their Sail & Sign account. Information on this fee is included in Carnival’s ticket contract.
Note: Electronic cigarettes or e-cigarettes are only allowed in the designated smoking areas.
For your safety, smoking is not permitted inside any stateroom or on interior private balconies on Oasis Class that overlook The Boardwalk or Central Park. Smoking is not permitted in any dining venue, food outlet, theater, hallway or corridor; nor in Central Park, The Boardwalk or The Jogging Track on Oasis Class ships; nor in the H2O Zone on Oasis and Freedom Class ships. A $250 cleaning fee will be applied to the SeaPass account if smoking has occurred inside staterooms or on private interior balconies overlooking The Boardwalk or Central Park onboard Oasis Class ships. Royal Caribbean International kindly asks all guests to please observe the non-smoking areas and to refrain from smoking pipes or cigars in any of the public areas. These requests are made to provide a comfortable shipboard environment for everyone. Guests who violate this smoking policy may be subject to further action pursuant to the "Consequences Section" of this Guest Conduct Policy.
Pipe and cigar smoking is only permitted within the Cigar lounge. (If no Cigar lounge exists on a particular ship, there will be a designated area for pipe and cigar smoking).
A guest must be at least 18 years of age to purchase, possess or use tobacco products onboard. Cigarettes, cigars and pipe tobacco must always be properly disposed of and never thrown overboard
We want you to be comfortable on board, so public areas throughout all our ships are smoke-free. If you smoke cigarettes, you can do so on your balcony, in the casino or in the Cigar Bar (where available). If you prefer pipes or cigars, you can smoke in the Cigar Bar or designated smoking lounge. Also, you can smoke cigarettes, pipes and cigars outside on open decks (just not around food venues, sports decks, kids’ pool areas and other designated nonsmoking areas). Smoking inside your stateroom will result in a $250 cleaning charge added to your onboard account.
Our smoking policy reflects our commitment to the comfort of all of our guests. Presently, all staterooms (cabins), showrooms and all other indoor areas are designated non-smoking with the exception of:
- Northern Lights Disco (ms Oosterdam, ms Noordam, ms Westerdam & ms Zuiderdam only)
- Seaview Bar (except that smoking is not permitted in the Seaview Bar on the ms Maasdam, ms Ryndam or ms Statendam)
- Sports Bar
- Crow's Nest (except that smoking is not permitted in the Crow’s Nest on the ms Eurodam, ms Oosterdam, ms Noordam, ms Nieuw Amsterdam, ms Westerdam or ms Zuiderdam)
While smoking is not permitted in staterooms, guests are allowed to smoke on stateroom verandahs. Smoking is permitted on certain other designated, outside decks. Cigar and pipe smoking is not allowed inside the ship; it is only permitted on the outside decks where smoking is otherwise allowed.
For all other cruise lines you can just go to their website and do a Search of "Smoking" and you can find their current policy.