I donated alot of money to the slots on the Iamgination last week (the dugy sitting next to me won over $2500.00, by the way) The machine, stating two days before we left had a scrolling message that kept reminding you to cash out your card. It was where your name and updated acct balances show up when you first sign on. plus, it was in the Carnival Capers. It was kinda hard not to know.
As far as the machines being tight, I dunno, people all around me were winning fairly big, I must have ticked off the slot machine fairies somehow!