Here is a link from the Guinness website from the U.S. The spoon they sell in their store is for "black and tans" - spoon

also another brewers offering - Saranac Black & Tan

There is no disrespect meant. It is an old habit based on a brewing history that is going to be hard to break, but I think education might help. I know that most people I've met from the other side of the pond think nothing of "smoking a fag", but that expression makes people here uneasy.