I have never received any of these offers but my sister has not paid for a cruise on any cruise line in the past ten years or so and she often gets deals for a second passenger. She plays poker every day of her cruise and sometimes spends eight hours a day at the tables. Apparently with poker they calculate how much money you have put down in bets for the duration of your cruise, it doesn't matter whether you win or lose just how much you put down. She is presently on a cruise out of Sydney, Australia. I suspect the cruise lines are doing well out of her but she says she does OK.