A small, stylishly dressed woman stands in a narrow corridor at the Los Angeles County Museum of Art, staring up in awe at a row of huge photographs of writers and artists, all persecuted or forced to flee Nazi Germany. Eyeing the melancholy visages of Max Beckmann, Franz Werfel, Ernst Barlach and George Grosz, she says quietly, “They all look so sad, like doomed men.” Stephanie Barron, the curator who assembled the museum’s widely praised “Degenerate Art” exhibit, explains that the art displayed here, which includes work by Chagall, Kandinsky and Klee, was loathed by the Nazis, who vilified it as “degenerate trash.” That phrase seems to strike a nerve with Barron’s guest, who wags her head furiously up and down. Of course, this isn’t any ordinary guest. This is the pop siren who’s been banned by MTV, blasted by the Vatican and nearly arrested in Toronto for simulating masturbation on stage. This is the wildly ambitious pop diva who began as a disco boy-toy and ended up as