On January 2nd, my wife and I planned to visit the Pompei ruins. We went to the Napoli Garibaldi train station ticket office to buy our round-trip tickets. Each ticket was approximately 2.50 EUR, so the total cost was EUR 10. I gave the ticket agent a EUR 20 bill. I waited for the change but the attendant didn't provide any. He started talking and gesturing in Italian and I pointed to the cost that is clearly printed on the ticket which was 2.50 (x 4 tickets). He then took us to the ticket office and asked his colleagues to explain in English. Of course, none of them spoke English. We went back and forth and finally I just gave up, took the tickets and boarded the train to Pompeii.
We were always on the lookout for scammers and pickpockets while in Naples but never expected the official ticket office to be in on it as well. It was only EUR 10 but still people should be aware. Next time best to ensure you have exact change. The train itself is commuter type of train that got packed really fast. We didn't feel unsafe and the trip to Pompeii took about 40 minutes.
Overall, we liked Naples, the food was incredible and people helpful but we were always cognizant of our surroundings. Our hotel told us not to venture too far away, by foot, in the evening. We didn't.