Scots is usually fairly intelligible, at least to the Scottish. Essentially, Scots branches off from middle english in a slightly different direction. But ver

Scots is usually fairly intelligible, at least to the Scottish. Essentially, Scots branches off from middle english in a slightly different direction. But vernacular Scottish - the language you'd expect to hear day to day on the streets - is modern English with borrowings (both in content and grammar) from Scots. And the scale of these borrowings goes a long way to define how "thick" we perceive the various accents as. So this leaves Scots with a few interesting traits. It can be easily mistaken for "just slang", because huge amounts of Scottish slang are near-direct borrowings. And this goes both ways, where the more slang you've been exposed to, the more you can pick out in Scots without actually knowing it. This leaves it being nowhere near as "foreign" as Gaelic, for example. (It also helps that Robert Burns was dragged out annually at school, leaving Scots as least as recognisable as Shakespearean English.) I'm not arguing that the Scottish "just know" Scots by default, or even that half of those who claim to know it, actually do. But there is a lot more exposure to it, or at least parts of it, than many people realise. It does turn out to be surprisingly recognisable (although I will admit, very jarring to see it written).