I lived in the Dominican Republic (its right next door) for a year and its very similar to Cuba. Trust me, its a poor country. You are probably going to stick to the tourist areas though so you probably wont see the super slummish areas. Also, locals never grow immune to the crap in the water and stuff, they just have never known anything else. I just bought big old 5 gallon jugs of water every couple of days, but like I said, you will be in the rich tourist areas where it will be a ton safer so I wouldnt worry about it. I completely agree with the person who said that the girls just see you as a walking visa, cause thats all you are to them.
~~~~~~~~~~~~~~~~~~~~~
Worrying is like a rocking chair. It gives you something to do, but in the end, it doesnt get you anywhere. Write that down.