The one time I was worried about being charged for rental car damage:
I walked into the hotel parking lot and saw a big traffic cone on the hood of the rental car. Not the small, knee-high trafffic cone but the big, chest-high one that looks like a big barrel. Along with the big, weighted black plastic ring at the bottom.
No idea who put it there or why. I thought it was going to leave big ugly scratches on the hood but luckily I removed it without leaving scratches. The rental car company did not charge any damage.