Pauline Viardot was, by many accounts (and photos), not a terribly attractive woman. Heinrich Heine wrote (when she still known as Pauline Garcia, before she was married) about her particular type of ugliness:
"She is ugly but with a kind of ugliness which is noble, I should almost say beautiful…. Indeed the Garcia recalls less the civilized beauty and tame gracefulness of our European homelands than she does the terrifying magnificence of some exotic and wild country…. At times, when she opens wide her large mouth with its blinding white teeth and smiles her cruel sweet smile, which at times frightens and charms us, we begin to feel as if the most monstrous vegetation and species of beasts from India and Africa are about to appear before us."All Ginette Neveu had to do to have a performing career (short as it was--she was killed in a plane crash) was play the hell out of the violin. She didn't have to try and glamorize herself.
Amy Beach was not a particularly attractive young woman
(though, as an older woman she did have an unusual sort of beauty), but she was able to achieve remarkable success as both a performing pianist and as a composer. It was her music that mattered, not her looks.
There have been legions of male 20th century performing musicians and composers who would have fit into the "less-than-attractive" category.
This photograph shows one male musician who definitely exceeds the standards of normal attractiveness, and one who certainly falls short of the parameters of normal attractiveness. Both men had tremendous talent, intellect, social skills, and ability, and both had great careers. Copland's looks never hampered his career (and Bernstein's looks never hurt his). The world of music is filled with the faces of men who were, even as young men, particularly unattractive. Of the 20th-century male composers and performing musicians I know with less-than-attractive faces, no one seems to have been unfairly judged as a musician because of his looks.
Women who appear before the public have always been judged by their looks. During the 20th century a man could get away with appearing clean and (sometimes) combed, and be judged by what he said (or in the case of a performing musician, how he played). Some women (and some men) have considered (and still do consider) certain less-than-attractive men tremendously attractive because of their intellect, substance, and power. A less-than-attractive woman has to try to make herself attractive in order for people to even consider her intellect or substance. If she presents the aura of being powerful (and she is not particularly attractive) she becomes particularly suspect. Consider Emma Goldman.
Consider what I call the Boyle Effect. Remember the hubbub that her looks caused, and the subsequent media obsession with her "makeover?" Consider the way Hillary Clinton had to slave over her appearance when she was running for president in 2008, and now that she has proven that her brains are more important in her current job than her looks, she doesn't have to waste her time trying to look 20 years younger than she is.
Now, in the 21st century, it seems that both men and women HAVE to look attractive in order to have careers as soloists. Never in my life have I seen so many photographs of attractive musicians in the "classical" field. Could it be that we are all simply getting better looking because of what we do? I doubt it. Perhaps the photographs are just getting better (not to mention the magic of orthodonture).