quote Dick Gaughan, SOME SINGERS WILL SING SONGS THAT WILL CALL ATTENTION TO THEMSELVES, some people will sing songs that they think people will like, and some people will sing the songs that they think matter and find the people who will want to hear them.
   an interesting statement but one that describes perfomance in too simplistic terminolgy, it is not as black and white as that, there are shades of grey.
perfomance is about variety and assessing your audience, it IS about singing the songs that matter to you but that does not rule out that you know the audience will also like them, you might be in a pub situation, not a concert you have to win an audience that was not there specifically to hear you.
approach has to vary upon situation, however he was right that you should never sing a song that does not matter to you as a singer.
A thought provoking programme that i have now listened to several times