I'm from Barcelona. Have seen so many people scammed and pick pocketed over the years. I have been robbed at gun point once in the US, and got some back up money stolen staying at a friend of a friend of a friend's house in Nicaragua.
Pick pocketers and scammers are usually easy to identify. The pick pocketer dresses nice, like a tourist or a respectable person, usually in couples. Girls with big tits, holding up a map, asking retarded questions, accidentally tripping or bumping into you, not respecting the natural distance, making a scene or smiling... The scammer always pretends to help you, help you make fast cash with a pick up the right card game, help you get an awesome deal. Sometimes he plays retarded, like he is going to sell you the 1.000 euro new dslr camera he is flashing for just 100 euro. Then there are other tricks, like the beggar who places a paper on the top of your table while you are in a terrace and you tell him to go away, and he goes offended, but your phone was under the paper and now your phone is gone. Or the beach thieves. All are VERY EASY to prevent. just by not keeping anything valuable on your day pack external pocket, how hard is that? Or putting your wallet and phone in your front pocket and have it under control. Girls not carrying the purse on their ass or side, but on the front... It costs nothing.