The Spanish Quarters of Naples are considered a no go area for tourists and in general not a safe neighbourhood to walk around in wheather you're from there or not..
But like with all forbidden fruits you can't visit Naples without taking a bite and at least get that one picture to show and prove to people that you were there!
If this sounds like you, or me, than at least make sure you stick with a few basic rules.
Don't wander around at night in the Spanish Quarter as it really is what they will tell you, dangerous. During the day make sure you know a bit...