I'm a fan of the AA franchise, and the "psionic residue" idea simply sounds amazing!
That would be true and it also could be use in order to solve a future case (i.e. a thief steals the magatama because it seems to be "an expensive object", yet for unknown reasons, he drops it, and once Maya and Nick recover it, she would have flashback-like scenes that would allow her to depict whom the culprit is, sort of a "gut feeling" she's just getting used to). Plus, it would be neccessary to tell if she's just having "images in her head" from such trace, or feelings within it as well (the nervousness and the need to kill a possible witness), which would help -and affect- her greately.