Amy Vanderbilt died in 1974 more then 30 years ago and was considered to be a US authority on etiquette...

Given that, I only can recommend that you US guys do refrain from having your regular excessive faith in US authorities only. Under the circumstances given I would put my faith in local FTer's authority and not in a lady publishing a book in 1954 and committing suicide by jumping out ot a window of her New York townhouse after she became aware that she published nonsense on the use of toothpicks in Europe for about 20 years.

It certainly depends on the country you are in an I have a certain educated feeling that it is more commen in the south of Europe as in the north. In the countries I am living in it would be nothing but very bad behaviour.