Hello Joe,
Unfortunately, the situation is alarming !
If you stay around in Chiaia and Posilipo (wealthy areas) this does not happen, but within suburbs, and other areas (like downtown) it is sad. Sorry, but it is a mafia situation....
If you plan to come south and still visit a few things in Naples and surroundings, come to sorrento and make it the hub for your trip, you can reach Pompeii, Herculaneum and other areas fro Sorrento. The city is calm and clean.
Take Care
Cinthya
ps. aside from that, I still love Naples....