Brad- CDC inspection is Center for Disease Control Inspection. It's kind of like a restaurant health inspection but more comprehensive. They look at the galley of course and make sure they are following all the cleanliness and health safety requirements, but they also look at the ships water generation systems, sewage systems, air ventilations, laundry etc... basically everything that could be a health risk factor. A 100 % would indicate that the inspector found no violations of code on the entire ship. Which is outstanding.
Most land based restaurants would not get a perfect score, so it is very good. There is a website that shows the scores of all the inspections for each cruise line, but I don't remember where it is anymore.
You would have to read what some of the inspections deduct points for to understand how difficult a 100% mark is to achieve. Anything in the high 90% range is very good.
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
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013