When it comes to human rights, anyone in a celebrity spotlight would be a great spokesperson. A celebrity will be able to draw attention to important issues, and increase support for a cause by getting their fan-base involved. Even though I'm personally not a fan of her music, Madonna is a world famous individual, and I think she'd be able to get a lot of money and support for human rights.
I believe Madonna is a good spokesperson for worldwide human rights. By far she knows far more about the problems of the world than many US citizens because she has seen it first hand. I believe she could spend more time in this arena and benefit different population, but ultimately that is a choice she has to make.
Madonna has always been a performer who does her own thing and seems to value unique expressions of human culture. No celebrity is more qualified to stand up for worldwide human rights except that his or her fame can be used to shed light on issues, and so Madonna is as good as any and maybe better than some others.
Madonna has had longevity in her career. While there are many who do not like her, she has always stood up for gay rights and many other great causes. Yes, she can appear to be a bit egotistical at times, I also know the good she has done for so many. Her voice can be a voice for good.
No, I do not think that Madonna is a good spokesperson for worldwide human rights, because she is just an entertainer who travels around the world. Her entertainment is not without controversy. It is risque for what it was. She is not noted for her politics or academic ability, so she is not the best person to speak to human rights.