Oh George. Your experience is one that many aboard cruise ships experience. The Montego Bay Freeport (where the ships dock) is one of the most bustling areas around. Why? The local leeches know this is where the tourists will spend most of their time and the prey on them right there. Your trip from the cruise ship to Doctors Cave took you down the "Hip Strip" of Montego Bay. This is where you can do all of your duty free shopping and visit Margaritaville. Again, a big tourist trap. This is the 1st (and most unfortunately) only sights that most cruise ship people see.
I also had heard of many "bad" things that go on in Jamaica. Just like any other city or country, you will have your bad apples but on the other side of the coin, there are many more good apples. If you look at my trip report that I posted above, you can see that there is much more to Jamaica than the Montego Bay Freeport/Hip Strip area. I have never felt intimidated on any of my visits to Jamaica which is why I love to go back. The people, culture, food and hospitality are second to none. You just have to get away from the traps.
Adam aka Big Dude