Places - Las Ramblas is all good and well, pick pockets are said to be more common here as it is a touristy area where people move slowly and in crowds. The big market - Boqueria (just off Las Ramblas) is great for street photography and has simply amazing produce.
http://www.barcelona-tourist-guide.com/en/albums-en/ramblas/pages/las-ramblas-17_jpg.html
The Gothic quarter again near Las Ramblas has some beautiful buildings. Wander in, get lost and then see where you end up.
Keep valuables in inside preferably zipped pockets and you'll be fine, in busy areas wear rucksacks on your front etc. Just be aware of what is going on. I had no problems with a 5D2 and a 24-70L so enjoy your self. Just make sure that you have valid insurance.
My friend was pickpocketed in the Gothic Quarter, in broad day light with me and another friend stood right near him. When we realized what had happened we headed back and a Waiter pointed out where they had gone... like he had seen it happen a million times before.
The other issue though, even with insurance is that you will probably need to file a Police report. There were ques outside the Police Stations we passed!
If you are wary and keep yourself locked away where nobody can easily pickpocket it from you, then you should be alright. I'd watch out at night though having your camera out of a bag. Las Ramblas changes into a different world at night, the market stall sellers all go home and it's replaced by pushy Prostitutes who will grab you (if you aren't with a woman) and men selling beers and drugs. They are all easy to spot though, as they aren't Spaniards. I was always worried that when these Prostitues and stuff came up, that they may also be attempting to pickpocket, which is why you have to shove them away. Seriously, it's bizarre!
Here's a couple of bad pics I took just from the apartment I was staying in on Las Ramblas.
These men are all selling cans of Beer hidden in bushes, however the ring leader had drugs stashed underneath the bag of a public bin.
The old guy was the ring leader, he took a cut of everything sold.
Couple of British Guys being grabbed by Prostitutes
This guy went down the back alley with the She-Male in the picture. He came back a couple of times as he was obviously making up his mind whether to go through with it or not!
Of all the troublemakers I saw, the only arrests were... this guy selling Samosa's
The Police also did a surprise raid, involving a handbrake turn and driving on the pavement to catch about 5 prostitutes, while about twenty just ran away!
Oh also just avoid eating at anywhere on Las Ramblas, rubbish food and overpriced. It was a good experience though and the architecture is fantastic.
), and as for what the women brag they can do! 