Well as Dwayne noted, I was on a cruise last week so I didn't reply. But I can now. And I am not going to say you didn't have a bad experience at the casino. (Lord knows I have had my share) But I will say that a dealer change itself is normal procedure and should not have affect the outcome at all.
I don't play slots. As an electrical engineer who has spent his career designing computer circuitry I understand how the machines work and how they could be designed to be very unfair. I am not saying they are, I am saying they could be. In the states, you have casino gaming commission that can regulate and control that and I don't have any issue with playing them in a land based casino in the states. However, as Dwayne pointed out, on the cruise ships, there really isn't any formal regulation the casinos would have to answer to. Now, the odds and the house advantage really makes it unnecessary for the casino to rig a machine but its not out of the realm of possibility.
As far as switching out the dealer on face up black jack? Why would that make any difference? You witnessed a random act of probability. They change the dealers on the tables very often (maybe more often than a land casino does.) but that does not change your odds of winning. While it may seem like the change in the dealers changed the cards (because it often seems that way) I have also had a change of dealers make things go better too. Unfortunately people tend to remember the change of luck for the worse. On normal blackjack where they have a continuous shoe then the dealer is only pulling the cards out of the shoe and dropping them on the table. It would be impossible for him/her to influence the outcome at all. For face up blackjack? I don't recall if they use a single deck or not. If they use the machine then the same comment applies. If they use a signle deck they shuffle and deal from then yes, it's possible they were cheating. But unless your new dealer was dealing from the bottom of the deck and was truly skilled at doing so, there is no way you started losing because of the dealer change itself. And IF the casino risked dealing like that they would be dumb. Can you imagine the lost revenue that would result from someone proving they ran a crooked game?
I was playing craps on the Conquest last week. We were doing so well they had to bring in a fill (more chips) for the table because we had cleared out most of the $5 and $1 chips. They had three pit bosses watching the table AND they were changing the stickman and dealers a lot more often than when we were not doing so well. They do this because the house is as superstitious as a gambler is. But we continued to roll well. Now.. had they tried to change the dice out... then I would have called shenanigans, but I know that the dealer has nothing to do with how I throw the dice.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise, Magic 1/14, Freedom x 2 6/14
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013