Stopped Walmart from ripping me off today. [View all]

Went for an oil change and the guy signing me in asked if I wanted new wiper blades or air filter, said no on wiper
blades and "let me see the air filter before you change it". Half hour later here he comes with my air filter in hand
telling me it's real dirty, so I pull my small flashlight out of my pocket and shine it through the filter, hell it was
almost brand new yet, looked at the guy and asked "Would you throw this away if it was in your car?"
He walked away with his tail between his legs.

That's how we always checked them in my father's service station, back then we used a trouble light with a 100
watt bulb, lot more powerful than my little flashlight.