Last night there was a TV report about the clipboard girls who frequent the queues at the Sagrada Familia. They carry a clipboard and ask money to build a new church. TV showed a foreign lady tourist get her purse and give them some money. So of course they now knew where she kept her purse. So one of them distracted her while the other picked her pocket.
All of these young women are trained pickpockets. Their only good cause is for themselves. Be wary of them and just say "No!".
They frequent other places where tourists go to, such as the ramblas.
These girls can be found in other big cities like Madrid. About 2 years ago I was in Madrid during Christmas time at Calle Serrano. I was with my wife and was going to enter a store. One of these girls put her clipboard in front of my face, blocking my entrance to the store. I shouted "No!" to her. She knew that I knew what she was up to. So she cursed me in Spanish and I said to her, "Llamare a la policia! (I am going to call the police)", which scared her off and she ran away.
Many of them are under 14, so the police cannot jail them. That is why the mafias use them.