Marijuana or Ganja(as it is called in Jamaica) grows naturally on the island. It is quite normal to be approached by a seller virtually everywhere and anywhere in the country. It is a normal,everyday occurance in Jamaica and in no way is it a reflection on the country or the fine people of Jamaica. Jamaica, being poor, results in many people trying to make a living by selling the contraband.
They are a respectful and kindly people, if you remain firm, they will, for the most part, leave you alone!
It is different culture! Don't sweat it Mon!
Relax and enjoy-it's a really great place!