the only spirit that does not smell, is odourless and tasteless and you could easily get away with taking onboard without raising suspicion to those checking bags and scanning luggage is Vodka and Coca Cola(in a coca cola bottle) or Vodka and Lemonade (in a lemonade bottle) as Vodka does not smell, its odourless and tasteless (where as Rum, Baileys, Archers, Tia Maria, Whiskey like Jack Daniels, Grey Goose, Groose, etc etc etc all smell, they have a colour and they have a taste to them even with Lemonade or Coca Cola or on their own). so the alcohol policy really is stupid and ineffective in a small way.
personally and this is my own opinion I think think its being done as a way to get rid of the in cabin fridges(apart from if you declare you will need one for medication) and to cut down on cruise ship recycling waste but if its to cut down on recycling waste they need to offer more selection of alcohol like whiskey, spirits, larger, cider, beer, wines and get rid of the champagne unless you are celebrating a big birthday like 18, 21, 30, 40 etc, or a wedding, or wedding anniversary, honeymoon and lower the cost of the drinks packages especially as most of the bottles of wine, spirits, bottles & cans if soft drinks they buy from Bookers Cash and Carry
Deluxe Drinks Package is now £60.50p per person per day (total for 7 nights is £423.50 or 14 nights total is £847.00 etc etc etc you get the gist)
Classic Drinks Package £48.85 per person per day so for 7 nights its a total of £341.95p or 14 nights its a total of £683.90 per person
Alcohol Free Package is now £26.95 per person per day so for 7 days the total cost will be £188.65p per person or 14 days the total cost will be £377.30p per person
the Refresh Drinks Package is a total of £14.45p per person per day so the total cost for 7 days will be £101.15 or 14 days the total cost will be £202.30p per person
and if there is two or more guests in a cabin each person must buy the same drinks package (quoted from P&O Cruises website)