Hi Jane,
I understand and agree with your concern for situations where there would not be value added with a finding like the one you wrote, and that's why I indicated the importance of the auditor's experience.
And that's the part where I agreed with you
But I do think an auditor has... well, if not an obligation, then some kind of responsibility (implied or otherwise) to be able to explain what it is they are checking for or seeking, and why they are following a particular line of enquiry. (I am also quite willing to be patient if they say 'after these questions have been answered/not).
I think your wording of it being 'entirely up to the auditor' worried me a little - I'm thinking of the fortunately not too frequent occasions when I have come across the type of auditor who wouldn't explain anything and acted very arbitrarily and high-handedly. Apart from anything else, being able to provide some kind of explanation to auditees is good practice I think, if not polite behaviour. I am
not saying that they have to get the auditee's approval (far from it!) - indeed, the auditee may not even like the line of enquiry, they may even disagree with it... but provided it's within the scope of the audit and the system, then at least giving some kind of reason behind it makes me feel reassured that the auditor does have good reasons for what they're doing (other than acting purely arbitrarily).