Richard...no, when an unaccompanied singer is slightly off of concert pitch, a guitar player 'tends' to ease them up or down into pitch, and the guitar player can then continue. I know one guy who has such awareness and control that he is NOT movable, and it drives the noodlers crazy. I have heard him start a song between notes, just to make the point....but he is the exception. I can't do it...I have no recourse but to ask them to stop if I want to 'do it myself'. If it is a simple well-known tune and I know the guitar player knows about the same tune, why it might be welcome, but not on EVERYTHING!