I know Rio well. Its slums, for complex reasons, are dangerous, unsanitary and extremely violent places. Around 5,000 people were murdered last year in the city, the vast majority in and around favelas. During the rainy season mud-slides kill others, destroying homes and property. The wily tourist is indeed relatively safe in Rio; a $50 tour of Rocinha - itself, in my opinion, in questionable taste as a kind of voyeuristic slum tour - will probably bring the punter back in one piece. But this misrepresents the situation in a city where poor people are forced to live in very difficult circumstances with the constant threat of violence.