When you come to Sao Paulo you can visit the city hiring a licensed tour guide. In Brazil our license as professional tour guides is issued by an institution called Cadastur.
You can always check if your guide is a licensed tour guide searching for his certification a this link: https://cadastur.turismo.gov.br/hotsite/#!/public/sou-turista/inicio
A licensed tour guide must have a certification like this one:
Giuliano Orlando is my name and I'm licensed tour guide in Sao Paulo, Brazil and in for the entire Brazilian territory