This is really good stuff from John Jay, of Wieden+Kennedy. Advertising is not a one-size-fits-all solution. And, trying to apply your "secret sauce" to every client isn't going to work. No client is the same, and each comes to the agency with different needs to solve. Listen to what they have to say, and find a solution that works for them. As much as you can't let them define your work, or you define their product -- you can't let your work become the definition of what you do.