The context of the following conversation is The landlord sent another bill even though Alex already paid their rent. Alex called their landlord.:
Alex says The landlord hired another stupid assistant..
The friend responds What makes this one so stupid?.
Alex responds The landlord sent me another bill even though I already paid our rent..
The friend responds Is the assistant in charge of billing?.
Alex responds I called the landlord and the assistant admitted her mistake..
The friend responds I wouldn't call her stupid, careless maybe, but not stupid..