Were some of those citations made to prove those findings wrong? Dumb question, but would be a shame to not be thourough when attacking bad literature.
Unfortunately, it's much harder to come up with better measures. Given a smallish corpus of a few hundred papers, humans could read through them and annotate each citation with things like, "cited to debunk", "cited to distinguish related work", "cited for general background", "cited in passing", "cited for result", etc. But computers are not yet very good at doing that automatically, so the large-scale citation analysis just does dumb citation-counting.