No, I don't think that really makes a case for using a song book while performing. Marty Robbins makes a bit of a gag out of the routine, and the way he sings the song tends to indicate that he knew the words a whole lot better than he let on.

There's a difference between singing at a folk club or at a song circle and performing, in the sense of doing a concert or recital for a paying audience. Over the years, I have attended concerts by such well-known singers as Pete Seeger, Richard Dyer-Bennet, Theodore Bikel, Joan Baez, Gordon Bok, Guy Carawan, Judy Collins, Peter Paul and Mary, the Weavers, the Gateway Singers, the Smothers Brothers, Peggy Seeger, Ewan MacColl, Sam Hinton, Jean Redpath, Lightnin' Hopkins, Marais and Miranda, Mississippi John Hurt—and on for at least a dozen more. In addition, concerts and recitals by singers in other fields of music, such as opera, art song, early music groups such as the New York Pro Musica, the Baltimore Consort, etc. . . .

Nary a song book or piece of sheet music in sight.

I have been singing for audiences since the mid-1950s in coffeehouses, clubs, concerts (without song books or song sheets), and television (with neither song books nor song sheets nor cue-cards).

So—what do you want to do? Sing purely for fun? Or sing professionally, i.e., for paying audiences?

There are different standards, and a paying audience is not going to respond well to a singer who comes out on stage and sings from a song book.

Don Firth

P. S. If you're singing in a folk club or song circle, find out what the standards of the group are and abide by that.