That's just what I said, common sense or maybe the better term would be common courtesy. I really don't care if someone doesn't wash their hands after using the facilities or blowing their nose etc. Just leave those hands off the same railing other use, and don't pick up food in the buffet, decide it was something you didn't want and put it back. In fact don't use the tongs others will use.
My wife teaches in the inner-city. Shes become a bit obssesive about sanitation. Yes she's one of those who carry hand sanitizer in her purse and uses it religioulsy even just before communion. I assure you I didn't mean any pun. It's paid off in that she has cut her sick time quite a bit.
On our last cruise, a guy lost his cookies right in front of us in the auditorium. The usher tried to get him to stick around until the medical people could talk with him while the clean -up crew did their job but he disappeared. It could have been too much sushi or Corona. He could have had had a GI illnesss however. I wouldn't have been happy if he passed that around.
To be honest, I was feeling a little nauseous at that show too but I think it was the thrid cruise in as many years that we were watching Uber Rossi