I have seen Racism in my day to day life. But I don't remember seeing it on a cruise ship. I will pay more attention to see if only American or European citizens in the gift shop. To be frank I didn't remember seeing any Americans on the cruise ship.
In the hair salon it was mainly UK and Australia. I know that for a fact because I asked. I did hair for 14 years and it's fun to talk hair with people from different parts of the world.
As far as entertainment on Carnival I remember that being a mix of people. In fact I remember the Carnival show Ticket to Ride
had a wonderful Filipino band that did the music of the Beatles in the show and because I'm me.
I found the name of the band they are Music Unlimited
. Here is a video of them practicing on the Carnival Miracle.