"... The negative overtones of the group can, however, be defined with greater specificity; to be precise, they consist at least partly of the impression that the mantic activities in question cannot be trusted to provide reliable information. Connotations of deceptiveness and unreliability cling to it, for instance, in eleven of its twelve occurrences in the LXX; one of these eleven, moreover, is Deuteronomy 18:10, which the author of Luke - Acts not only knew but was conspicuously fond of. In this light, associations with falsehood should almost certainly be inferred from Acts 16:16 as well, so that anything the slave-girl says in this context ought to be suspected of deceitful intent. Thus, when she is cited directly afterwards as describing the missionaries as heralds, her meaning is most probably ‘a way of salvation’, the implications of which flatly contradict the position of the narrator and heroes of Luke–Acts. Indeed, as the implications of this phrase stand at odds not only with the soteriology of the implied author but also with Jewish monotheism, Paul’s annoyance at the girl can be seen from a Jewish perspective as not merely excusable but exemplary ..."

Klutz, Todd The Exorcism Stories in Luke-Acts: A Sociostylistic Reading (pp. 225-226) Cambridge University Press, 2004