The caricature of your brand
Cory has a post that points out research demonstrating that police have better luck finding suspects using caricatures than boring sketches.
A caricature falsely highlights various anomalies while diminishing the boring parts. So Jay Leno gets a ridiculous chin, or Jimmy Durante gets an even bigger nose (okay, he had a pretty big nose).
The same is true for your brand, but even more so. The best brands are caricatures of their true selves. Yes, they must have exceptional 'features' (a step that's easy to skip, but without which leads to failure) but then, over time, those features become a caricature. During the formative days of Fedex, the caricature was that their drivers would even rent a helicopter to get just one package delivered on time. It's easy to turn Starbucks' variety and focus on your needs into a caricature as well, "half-caf, extra hot, short macchiato, extra foam, with soy, in a ceramic mug...."
As Nixon discovered, when the caricature becomes negative, it's almost impossible to escape (glad I'm not Bob Nardelli or a shareholder at Topps hamburgers). Worse than avoiding the negative, though, is the tendency for most organizations to resist creating a brand that can be caricatured. It doesn't feel safe or responsible or prudent. Coloring inside the lines and pleasing most of your customers most of the time almost guarantees you'll be bland.
It's a lot cheaper and faster and more effective to have a big nose.