I think what he's getting at is this:
Situation: The clients tell you that their current advisor asked for money once, at a specific time in the past.
You say: Если бы вы были моими клиентами я бы не попросил денег.. - "If you were my clients I wouldn't have asked for money (on that occasion).
You say: Если бы вы были моими клиентами я бы никогда не просил денег. -"If you were my clients I would never ask for money." (at any time, not just that specific occasion)