I've been thinking about posting this since I got back, but just got around to it.

Switching planes in Minnesota I heard a seemingly nice woman whisper to her husband, 'See that guy in the kilt? That's the Ancient Grant tartan. My brother has that one.'
Considering that I was wearing the Macdonald Modern I was a little surprised, but I didn't feel any real need to correct her.

Cut to getting off the plane. She taps me on the shoulder and says, 'So you're a Grant, huh?'
'No, I'm a Donald. This is the Macdonald Modern tartan.'
She lifts an eyebrow and, in a terribly condescending voice, says, 'No. You're wrong there, honey. My brother has that same kilt and he bought it in Edinburgh. Paid a lot to have it made just for him. Someone's ripped you off 'cause that's the Ancient Grant tartan.'

Now, I tried to be as polite as possible and assured her that while the two tartans could be similar, I was positive of the tartan I was wearing but thought the Grant tartan was lovely, too.
At this she took great offense and accused me of trying to steal the Grant tartan and pretending to be Scottish when I obviously have a fake accent.

I'm not particularly annoyed by this and I know it's rather an extreme case, but it got me thinking.
Has anyone else out there met tartan-know-it-alls who are one Balmoral short of Kilt Police?