go and have a fabulous time on Costa, I know we did just that on each and everyone of their cruises, and as I said, their food selection in general is just great. If you are like us and like ethnic food, you will love Costa! And who knows, when you come back you might be able to speak a word or two in Italian or Chinese.
As for manners, I would not be too concerned about that, different regions of the world are accustomed to different ways of doing things.
I hate to put it this way but when we rubberstamp "foreigners" for not living up to our way of life, no wonder they think of us Yankees as being arrogant. The way I look at it, if you are visiting my country, respect the way we do things here in the States, if I visit your country, the omen is upon me to respect the way you do things in your country.
Just my opinion.