The CDC randomly inspects cruise ships to prevent the spread of stomach viruses. So far, in 2024, it has given 19 cruise ships a perfect score.KARIM SAHIB/AFP via Getty ImagesThe CDC randomly inspects and scores cruise ships to prevent the spread of stomach viruses.So far, in 2024, 19 cruise ships have received a perfect score.Norovirus can spread quickly on packed vessels.Cruise ships don't always have a squeaky-clean reputation for being ultra-clean.