Instead, you're a stranger. So, for my shaman, all the Tillers factions, or all the Tillers themselves, consider me a stranger, despite the fact that the red bar shows 0/8,400 and the reputation level is in red.
I think this is rather sweet, and reflective of the kind nature of the pandaren -- they haven't met me yet, but they have no reason to hate me, I'm just a stranger! I don't yet know whether the reputation required to move from stranger to best friend is any different to the reputation required to turn a hated reputation on its head, but it makes sense that it might be.
But don't worry, the Netherwing, Kurenai and Sporeggar still hate me. They haven't come over all fluffy.
[Thanks for the tip, Drakkenfyre!]