As an auditor, How do u reject politely for a 'guide tour' of the company? Maybe due to tight schedule.
As an auditor you are expected to plan the audit and submit an agenda. So, there should be no time scheduled for the tour in the agenda.
If you want to make it EVEN clearer, you make a note in the agenda that no tour will be performed due to a tight schedule.
Some auditees love to make plant tours extra long because they realize, the longer the tour, the shorter the audit and fewer chances of nonconformities being uncovered. Having said that, as an auditor, whenever I went to a new site FOR THE FIRST TIME, I always found a tour beneficial. But I kept the time spent under control and never allowed the auditee to prolong it, unnecessarily.