I'm tickled by the idea that a) Arthurian romance was set in a specific time in history and b) someone can accept that magic exists in that world but not glass (or black people).
Or how people can't accept that a Transformers movie could never be good because it was based on a cartoon.
Or how people complain about the continuity of a science fiction TV series set in the future.
Or how 'I can't believe it's not butter' actually isn't butter.
When in Rome. When in Camelot. When on the Enterprise.