In other words, are they all cloned from the same original? I can’t see how they can be so consistently good. 
Most commercial fruit is cloned from a single original. This is nothing special to melons or avocados.
Anyway, isn’t the quality of fruit more dependent on growing conditions … soil quality, amount of sunlight, water and drainage, and pest control … than minor genetic variations? It sounds like King of the West is just good at farming.