> Pretty common in every brazilian big city.
Pretty common in most non-OECD countries! I saw it a lot personally in Africa, carpet full of small items like sunglasses as you say, when the police comes they take the 4 corners of the carpet, turn it into a big sack o' stuff and haul ass! Shopping resumes at another corner :)
EDIT: the cardboards they are running with are like this (this one selling CDs with MP3 music): http://i1.r7.com/data/files/2C95/948E/3959/6CE2/0139/59E6/DA...
Pretty common in every brazilian big city.