Dear Corporate Training Consultant Person:
The next time you give one of these seminars teaching employees of multinational companies how to work better in teams, where handling cross-cultural differences is one item on the curriculum, perhaps you could lay off the ethnic humor, eh? Crude remarks about the Scots, directed at the one Scottish employee in the room, may be considered inoffensive banter in the UK, but in my own culture, it makes a bad impression.
η I asked the Scot in question, and he said that a lone Englishman surrounded by Scots would get the same treatment in the opposite direction. So it is inoffensive banter in a UK context. But still, where nobody else is in on the joke, it looks bad.