The last time I was there, there were several vendors set up in the park directly behind the Sagrada Familia in Barcelona selling fake Rolex watches, counterfeit Gucci handbags etc. Is that what you are looking for?

I also found the same thing in places where they have a 'market day' with open air markets. There's one near the Traffic Circle / interchange at the entrance to Barajas pueblo from the west. I also found one in Comillas (Cantabria) but it was 'market day' only!