This is a quote from Al Ries, taken from an interview with a PR pro, Marsha Friedman.
Many, many, many brands today do not stand for anything, because they’re into everything.  If you’re into everything, the brand can’t possibly stand for a single thing. Yet what’s the trend in business today?  Expand the brand.  Why?  Because it makes sense!  “Well, we want to grow,” they say. “So if you expand the product lineup, you’re going to grow.”  That’s logical.  But it doesn’t work and that’s the most important thing about marketing.  Every single principle of marketing is not necessarily logical and it makes it a very difficult discipline to learn, because almost everything you should be doing doesn’t necessarily make sense, if you look at it from the obvious point of view. 
The lesson? Do more with less. It does seem backwards but keep the confusion to a minimum and it works. Keep the promise simple.