If it's a specialty cruise, maybe.  
But if it's a single's cruise, well people are there to hook up.  
Most of the regular type of cruises are filled with couples.
Supposedly, the male crew members get a lot of action because of the single females.
There is a sub section of retirees, read an article about this a shot while back, that just lives on cruise ships.  Guess it's a lot cheaper than assisted living.
Great idea.  Don't think that it's a feasible work option.  
It's been written about.  If I remember where, I'll provide a link.
Feeling lazy this afternoon.  
 
Hugs,
Elisabeth