This is a very touchy subject, I know that.
Certainly though reasonable people should wish to dress nicely for a dinner in an elegant atmosphere. Jeans should be fine for the casual buffet on the lido deck, but NOT in white table clothed dining room. What sort of people would wear jeans to a formal affair anyway? Kind of like the Garth Brooks song " I showed up in boots to your black tie affair" or some sort of Jeff Foxworthy joke.