I have read some of the reviews about Carnival and find them funny.To rate the quality of the people on a ship really shows more about the person writing the review, than about the ship. I have gone on 20 plus cruises on all lines and there have been good and bad ships on all.
Just that a look at the government food inspection ratings on ships, they list Princess and Holland America had a major virus outbreak, as did Celebrity etc.. So all cruise lines have problems. I have found the Carnival Victory, Destiny and Legend to be fun, clean with numerous dining alternatives.
So every ship line has good and bad days.But according to the government inspections Carnival is doing a good job.