So wasn't Dana Plato.

Uh...NO.
she was a semi-famous cast member on some bullshit show for a few years. Miley Cyrus is a huge star who sells millions of records and sells out stadiums.
She's had a few risque (professionally shot) pictures published,which was obviously orchestrated to get her past the squeaky clean Disney image. BFD... not exactly a one way ticket to being a washed-up prostitute. Madonna has done far worse and she's 50, rich beyond belief and still touring.