that's always disadvantage of sightseeing with locals wherever it may be , good that you pointed it out .
Even with most excellent guides you are bound to wear their glasses so to speak.
And I'm sure that if somebody asked us to give them a tour of Bangkok, we 'd find a way of showing them Patpong, Silom and Suriwong even if they were our grandparents or their friends.
And as always , Master of Suspense is at work !