We've all heard the phrase, "don't trust a skinny cook." I know many phenomenal skinny cooks (my wife being one of them), but that's beside the point. The point of the saying is that you shouldn't trust someone that claims they specialize in something when they're demonstrating something entirely contradictory.
The other day I saw a windshield repair company advertised on a company car with a cracked windshield. I've also seen journalists that can't distinguish the different between "too," "to," and "two," and exterminators with their own bug problems. These sort of demonstrations certainly don't lead me to believe that they actually know what they're doing.
Going beyond what you should be doing just to protect your reputation, what are you consciously and purposefully doing to demonstrate your service (or product) to potential clients?