Green Apple Skittles were basically like saying "what if our candy occasionally contained pieces of poop?" If I wanted that I would just eat licorice, thanks.
The only reason I came back to Skittles at all was for the Sour Skittles, which are delicious. Sour lemon and sour strawberry are the best Skittles flavors. However even sour green apple is edible once all the other Skittles are gone.
Also I generally eat the Skittles a couple at a time to get a complex melange of flavors, like a true Skittles connoisseur.