So customs won't hesitate to fine people who have undeclared food in their bag - regardless of whether they put it there themselves or their partner packed it. Why do you think Customs would be any different with such a clearly

worded request like "cough".
And, yes even one cough picture can only take a couple of mins to find.
My problem is with the wording of the restriction - not the physical intentions of the restriction. It's a poorly thought out "catch all", with potential for abuse by Customs staff.