Those "hidden" windshield cracks...
I've rented enough rental cars over enough decades, including from those located in the usual airport "darkened" garages, to know to do a pretty good inspection and take photo's before selecting a car and driving it off... but color me foolish on a recent Hertz rental at LAS... after selecting the car of my choice, giving it the once over, taking photo's of the exterior, taking photo's of the fuel gauge, odometer, sitting in the driver's seat and looking up through the windshield to make sure there were no visible cracks, etc., color me "humble" after a few hours out on the road, when I put up the driver side visor and to my "horror", found what it was hiding beneath the down visor on the windshield, see the below... will add to my checklist, to make sure the visor's are UP so the complete windshield is visible when making my check-out inspection! Can't even trust a visor these days...sigh 
Of course, when I returned the vehicle I made sure the visor was DOWN, will leave it for the next renter (you?) to discover the "surprise"...
don't forget to check what lies behind the down position visor...!!!!!!