From what I have read they are true. From what I have heard from a few friends they are true. And from what I have experienced very briefly outside of Brazil they are true.
1) The girls (guys could be in this legend, but I wasnt paying attention) in Rio are stunning. Especially, being blunt, their bodies.
2) Brazilians are very warm, open, full of life people. I have experienced this already outside of the country.
Results: I walked along Copacabana and Ipanema beach for a complete day. I felt as if I were at a beach named Big C in my hometown. I didnt even see one body that turned my head. I was dumbstruck...and I broke my third pair of sandals in as many weeks somehow.
Onto the second assumption: The first contact with a busman was horrendous. He almost refused to give back the due change. But he did so after asking for it, with an ugly expression.
Later on, at night, a waiter would barely mutter a word to my friends and I. He offered no help or explainations either.
Onto hunting for the true legend...