I personally feel like they tattoo themselves up so no one will shoot them and then they don't have to personally make the decision to not to do scenes anymore. Like an addict that can't say no. If I fuck up my body enough, no one will want to shoot me for money. Dakota Skye is the latest example of this phenomena.
I seem to remember Janine Lindemulder saying that exact same thing when she was on Stern a long time ago, like before she even went to jail. I guess it depends on the whore because Janine kept getting work.