The closest I have come to a Scotsman being "offended" by my wearing a kilt is when I was wearing the hand sewn kilt I recently made fro Ren Faire usage. I was at a Celtic shop in Wells, Maine. The gentleman running the sho at the time asked, "What tartan be that, lad?" To which I replied, "It's not, really. I just thought it was a nice pattern and that it would look good as a kilt. I made this for Ren Faire."
That was all he had to say about that. Then, to my surprise, he helped me pick out a kilt pin. He didn't even recommend the most expensive one he sold.