Perhaps it is an oversimplification, but I have come to teach that a key
identification mark of datives of indirect object and advantage is exactly
what Carl notes here, namely that they refer to persons. Thus far I haven't
found any exceptions that seem to be better described as datives of indirect
object than with some other syntactical category, but my search has been
restricted to the NT. If someone has some clear cases that might not fit
this picture of datives of indirect object, hopefully they will share it so
that a more precise idea of exceptions to the general usage to persons can be
established.
Bill Warren
Professor of New Testament and Greek
New Orleans Baptist Theological Seminary