"To avoid being blamed for damage you didn’t cause before you rent, Mr. Hirota recommends consumers use their smartphone cameras to take pictures or video of the car’s condition before they drive it off the rental lot, and again just before they return it."
I was doing this as a matter of routine and glad I did. I picked up my rental at YYZ and had it for two weeks, during that time someone scraped the side of the car in a lot. I returned the vehicle and filed a report for the damage to the door and flew home. My insurance contacted me about a $8000 claim for damage all over a rental car. I sent all my pick up and drop off pictures to the adjuster and they demanded details from the rental agency. The rental company was trying to claim every bit of damage ever done to the car, even little dings that they said they don't penalize the customer for.
I sent a letter with pictures to the regional HQ and they dropped the claim entirely and gave me a free week.