Which can be done without conducting an audit of their books and records.
That IS what an audit does. In an audit you go beyond the financials, and at best, you inquire with the client.
And in many cases you don't know if it's wrong or not. And nothing requiires you to investigate the claims of the client to the extent that you are performing an audit function.
If my inquiries of the client do not satisfy me, and/or the client doesn't want me to make the changes to their tax return, then my option is to let the client go.
Ah. So you did look up the word.
I take my clients word that the information they provide is accurate and complete. And while I may move things from "auto expense" to a capital asset (like the purchase of a vehicle that gor booked as an expense), I am doing that once again, based on the clients representations and not based on any audit proceedures.