I've been thinking about this. Looked up some of the past mascots, and what many considered the best ones. Reminded me of visual communications, so I made up a rule:
If it takes more than three sentences or 20 seconds to explain your design, you've failed. If you need a whole CG video to explain even what your design is, that should be a clue that you need to start over.
These widely considered "best" mascots were representative animals, sometimes wearing representative colors. They needed no explanation: "This is a Russian Bear. This is a Korean tiger. That there is a 'Merican Bald EAGLE." etc etc.
The widely considered "worst" mascots were those who were difficult to identify and were heavy on the symbolism: Athena and Phevos of Athens were based on ancient statues, but nobody in their right mind would know that off-hand; it had to be explained why they were so ugly. The much loathed Izzy of Atlanta wasn't even supposed to be anything, which had people naturally asking, "what the frak is this thing (and why is it so ugly)?"
In summary, after much consideration, I must aggree with Nuke:
KILL IT WITH FIRE!
