Isn't part of the problem that words such as average, mediocre and adequate is mostly used to refer to bad things?

My favourite joke from Community is in an episode where they are shooting a commercial for the University and how this gets completely out of hand.

In the end, when the review commite sees the final result one guy says "It's good" and the other chimes in "It's better than good, it's good enough"

This is funny because "Good enough" is usually not considered to be good.