On the rare occasions when I actually encounter someone seriously saying "If you [insert arbitrarily chosen behavior here] you'll go to hell!" I like to just take the opportunity to ask "so, what you're saying is... Jesus died in vain?"

As for the tartan vs solid color issue, I've actually had fewer people notice the solid color kilt. I'm guessing that's because it's black, and doesn't always grab your attention. And it may also have to do with the fact that if they don't recognize it as a kilt, they are less comfortable asking about it. When they do notice, the reaction is about the same.

What I do find odd is that more people ask if I'm irish than scottish. But either way, it's a good chance to practice a phony accent.