It is really funny to see tourists on the beach, they find everything so different that the look on their face is priceless. It is impossible not to recognise who is Brazilian or not. However, cities like Rio are very used to receiving tons of tourists, so they will have police taking care of the nice places people go (Copacabana, Cristo, Pao de Açucar, Lagoa, Barra, etc); the problem is that they get so dazzled that they forget to take some very basic precautions. You cant pay a coconut water with a 100 reais bill and then leave your wallet out there to swim, of course your wallet on be there afterwards.... Deep shit (like murder or rape) only happens with people who risk their lifes. If you are visiting an unkown place late at night and you are feeling unconfortable, just get the fuck out of it. Dont fucking risk it only becuase the view is gorgeous or because your friends are saying you are a pussy!