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?
The end may justify the means as long as there is something that justifies the end.
—Leon Trotsky