Simply having the auditor's report conveys to your prospects that you're speaking their language. But meeting their needs at every level earns and keeps a client's trust and builds "brand" with every interaction. A focus on the customer is the most powerful way of winning and keeping that customer. This sounds like a marketing talk on purpose; marketing experts understand the importance of a consistent message of excellent results. And what is an audit but proof of consistency?
... I'll let you in on a secret. Big people are exactly the same as little people. They're selfish, squabbling children whose motivations are jealousy and greed. No one becomes big when the hit adulthood. They just become better at hiding how small they are.