Larry suggested that if there was not a valve she might want to install one. You stated, "When the refrig is out and your are installing a shut off back there,..." leads me to believe that you know something that the rest of us don't. Write what you mean. In fact, her post indicated that there is a shut off valve present. A compression fitting is just that... brass compressed against brass with a threaded nut. If the threads are "screwed up" it should NOT be used. Teflon tape should NEVER be used to compensate for crappy threads, stripped, or whatever. Besides, if there is a leak all the Teflon tape in the world won't do jack to stop it.