Gladys is pretty bad, only because it is old-timey sounding. Other names that would also be bad for the same reasons: Gertrude, Margaret, Elizabeth, Abigail, Mary, Beatrice, Helen, Mathilda, Penelope, Bertha, Hortense, Mabel, Mildred, Millicent, Phyllis, Zelda, Karen, Katherine and any of those odd hyphenated names that girls sometimes get, like Betty-Sue or whatever. They'd probably make me feel like I was in a geriatric strip club.
However, as far as stage names go, the first that sprung to mind after reading the thread title was "Streaky".