Indeed, the inquiry resistance typically recurses. For in addition to the unclarity of the borderline case, there is normally unclarity as to where the unclarity begins. A 1.8 meter pygmy is tall for a pygmy but a 1.8 meter Masai is not tall for a Masai. Although relativization disambiguates, it does not eliminate borderline cases. There are shorter pygmies who are borderline tall for a pygmy and taller Masai who are borderline tall for a Masai.
Words are only vague indirectly, by virtue of having a sense that is vague.
This contrast between vagueness and ambiguity is obscured by the fact that most words are both vague and ambiguous. The contrast is further complicated by the fact that most words are also general. Generality is obviously useful. By gauging generality, we can make sensible trade-offs between truth and detail. This precipitates many equivocal explanations of vagueness.