So , Al, I sing tradtional songs but disagree with Martins quote. I believe that is important to have respect for and love for your songs trad or contemporary,and that involves [practising and trying to perform to the best of your ability.
some people are more musical than others, but i believe that most people can put in competent perfomances if they work at it, that is all i ask, and to say
"You cant damage a song by singing it,the only way you can damage the song is by not singing it" is imo wide of the mark
he probably meant that a good song will continue to be sung despite the occasional incompetent performance of it