Yep. My sister used to work as Head Cashier on Carnival cruise ships in the US, and confirmed this.
She also told me the story of someone who came up to the cashdesk with her big bucket, which is usually full of their winnings from the slot machines. She just pushed it over the counter to my sister and walked off. It was brim-full of puke.
The woman had a stomach bug, but couldn't let that stand in the way of spending her every waking moment sitting pumping coins into the slot machines.
(I was on one of the cruises when my sister was getting married. I couldn't believe the Americans who spent all that money for a cruise and never left the gambling machines the whole time. They never enjoyed the entertainment, the pools, the sunshine, or the excursions at every port we visited. I guess that's addiction for you!)