Well, at least it would be honest and their followers wouldn't be led to believe they are interacting with this girl if they aren't.
Its not much different if you were a fan of a singer and then found out they are lip syncing it all and not the real artist like say, Milli Vanilli.
You buy the CD's, pay for the concert tickets and merchandise and find out its all a lie. You feel cheated and lied too. Insulted and duped and no one wants to feel that way.
So would you rather continue to feel duped or know the truth and stop supporting a fraud? I'm not sure which one is better. Everyone cold have continued to listen to the fake Milli Vanilli music and paying out more money for fraudulent work. And most likely finding out later anyways since the truth always comes out eventually.
And remember Ashlee Simpson getting caught lip syncing on live TV? Imagine all those fans she had all being disappointed and lied too.
Its unethical to take money from people knowing that what they are paying for is a lie.