The Merriam-Webster Usage Dictionary makes this note:
By all accounts the subtractive sense is the prevalent one in 20th-century English, but in many particular instances it is hard to be certain if the subtractive sense rather than the intensive sense was intended [...] You would think that the coexistence of these two uses would lead to problems of ambiguity and confusion, but in practice this seems not often to be the case. For although the lexicographer must try to determine the exact meaning of each occurrence of a word, the reader is under no such constraint. The distinction between the two senses is not always crucial to a general understanding of the sentence; when it is, the reader has the larger context for help. And the writer can always use a negative with quite when he or she wants to emphasize a falling just short.My future mother-in-law pointed this variance of meaning to me, and her personal usage note is as follows:
When I use "quite" with words which could not normally be accompanied by "very", eg. remarkable, dead, awful, finished, pathetic, stunning, all right, amazing, - quite would tend to take the first meaning, one of emphasis. But the rule doesn't always work - "quite good" virtually always means somewhat good, unless expressed in a surprised tone of voice, in which case it means "better than expected" (and one's standards did not start off particularly high). "Quite nice" is dismissal; "quite delightful" is praise.
Could it be that "quite" accompanied by a strong term of praise or disapprobation usually gives emphasis, but accompanied by a weaker term, (nice, good, pretty, untidy, plain) it modifies the term to be weaker still?Indeed, tone of voice is important for all sorts of communication (sarcasm, flirtation, anger, etc.), which still makes a written "quite" difficult to interpret. It's one of those ambiguities we just have to live with unless the author is alive to question.
This one is going to take a quite a little thought. Quite a little means "a lot" Quite a lot means "A great deal." One thing I am sure of. Used on its own, "Quite" indicates agreement, but not necessarily friendly agreement. It's all in the tone of voice.