> I'm curious if "esquivalience" or "dord" (another example) have been used in error to support their fictitious definitions, thus becoming suitable for inclusion in newer dictionaries.

This would be interesting: Can adding a word to a dictionary be a method of introducing it into the language as it is actually used? I don't know, and, you're right, nobody seems to talk about that. This is the kind of thing you need corpus linguistics to figure out:

http://en.wikipedia.org/wiki/Corpus_linguistics

> Corpus linguistics is the study of language as expressed in samples (corpora) of "real world" text. This method represents a digestive approach to deriving a set of abstract rules by which a natural language is governed or else relates to another language.

Finding out how (or whether) a given word is used is right up that field's alley.