I can't believe Joyce didn't even notice that "Buffy" was acting weird and that it wasn't her at all in Who Are You I mean one sign you could tell it wasn't really Buffy the way she dresses. Buffy would never wear those kind of clothes all that black and the leather pants.
E
Enemies
Buffy wears red leather pants, black vest and leather jacket when she goes to kill Faith in Graduation Day Part 1