So if your air filter was dirty clogged and black you wouldnt want to know about it? Its also the service advisors job to tell you if the technician finds anything while doing your oil change, which in turn, means he will be trying to sell you the parts you need. Its their job. Most places, if they are run right, will not sell you something you don't need. We dont do it at my dealership. i know there are some out there that do but dont throw us all into the same category.