TGS: What's with the code switching?

[Dominik]

Have you noticed how the Gunslinger seems to be changing his speech patterns completely arbitrarily? One second he just speaks plain modern English, the next it's all "Yar, I talk so I tell ye". I figure it might be to indicate his switching from "common" to that high speech that is mentioned a few times, but that's never made very clear.

[Leesa]

That's exactly what's going on.