I'm no expert, but it seems to me that the booing is mostly down to different cultural expectations (i.e. Brazilians don't necessarily see it as disrespectful):

I'm no expert, but it seems to me that the booing is mostly down to different cultural expectations (i.e. Brazilians don't necessarily see it as disrespectful): http://www.bbc.com/news/magazine-37026844 http://www.bbc.com/news/magazine-37026844