I am an avid eater of coconut... Well, I would be if I had some decent coconut to begin with! It happened quite a few times that when I bought a coconut in a supermarket (you know the brown, ripe fruits? - well, here in Europe there is no abundance of fresh coconuts), and when I ate its content... it tasted like dish-soap (eeek!). How can I be sure to select a coconut, which won't ruin my day?
Those at the store should be heavy and 2/3 full of milk or more. So shake them and listen, and also judge the weight, holding them in one hand.
Once you buy a coconut, place it between a rock or three. Make one slice with a large heavy knife to remove the top and the top hull inside the outer hull. Pour out the milk and chill if you wish. Then cut the coconut in half. Scoop out the meat. It should be firm but soft. Place that on a plate or eat with your hands.
When harvesting, after dropping a bunch of coconuts, you select the ones whose outer hull is 1/3 to 1/4 brown. Those you sell locally. The green ones you take to the road to sell to the waiting trucks. Those are for shipment.
All extra coconuts should be saved for making coconut rum. The outer and inner hulls are saved for cooking and coconut charcoal. Any that drop from the tree and split open go into the rum also, or can be used as pig fodder.