Jack, what is is that people find so 'alien' about Scottish slow airs?

I don't know. To me, they're all part of the same idiom as the dance music (which people never have any problem locating in time and space). People's perceptions of music are much more context-dependent than they are usually willing to admit, and the old slow airs are performed so rarely there isn't a standard context for them. Perhaps if I was playing them on an accordion and wearing a tartan waistcoat, listeners would find it easier to fit them into their conceptual scheme.