Esther was attractive to everyone who saw her. The fact that she was quite unhappy with her situation dimmed neither her beauty nor her personality. Esther's appeal was universal, nor merely ethnic. People from countries throughout the kingdom automatically assumed that she was one of their own. Every tongue in the palace was filled with praise for her.
Esther was able to attain this because she had a deep inner love for all humanity. If every man was created in Hashem's image, she must love every man as she loved Hashem. Even when she became queen, she was humble. She treated even the lowest commoner like a long-lost member of her family. She would ask about each one's welfare and sympathize with his troubles. This in itself made everyone feel comfortable with her and treat her as a countryman.