Sim Reader What All Can A Sim Card Reader See Or Read?

What all can a sim card reader see or read? - sim reader

My friend thinks. It has a Samsung Juke and their parents a SIM card reader. She wants to know whether their parents can read deleted text and instant messages or other messages you've sent or received on your mobile. not depend on what your Parnet freak just for nothing. Thank you for your help. All links to Web sites would be great too. Thank you a bunch