I think you missed the op's point. It wasn't that you can't have a less then perfect cruise. It was about the number of people who go on a Carnival cruise then complain, that its not the same cruise you would have on Cuarad. We had a couple at the table in the MDR on cruise who after the second nigh wouldn't eat in the MDR. Thier complaint was that guys were aloowed to wear polo shirts and slacks. They claimed it being a cruise every night a gentleman should be in at least a suit and tie. As the OP was saying their complaint was that they had the worng idea of a Carnival cruise.
2004 Carnival Imagination Grand Cayman/O.R. Jamica
2006 Carnival Valor Eastern Caribbein
2008 Carnival Liberty Exotic W. Caribbein
2010 Carnival Spirit Mexican Rivera
2012 Carnival Freedom Exotic W. Caribbein