Thinking of yourself as an advocate for the customer! There are consultants that do this.
You ever see the person that takes on the $250,000 renovation job to their house and they decided they had the skills to be the GC? All too often people feel they are qualified to make that decision- and rarely do they seek the advice of someone who is more knowledgable. Everyone wonders what's your angle.
I think it's a great idea. I'm rarely a pessimist, however, I have to ask how many people are already too dangerous for themselves because they think they know enough to make the decisions. There has to be a market - and like anything else, it would take time to build/develop a reputation to the point where people would come to you for the service. But you certainly would have to figure out a way to make sure there was no conflict of interest on your behalf (kick backs, buddies doing the work, etc) - as this might spoil the trust with the client.
Lawn Lad, Inc.