Most places we eat at wipe menus off after each customer. The fact is, while these are significant sources, most healthy people won't get sick. There's usually not enough of the microorganisms on things to infect someone, but it can happen on occasion. Poor food handling is a bigger issue overall and the cruise lines have that down. We've caught a few colds over the years and at least one time someone admitted several days into the cruise that they had a cold when they boarded and they had shook my DH's hand at dinner the first night. And, my DH caught a cold about 3 days in.