What’s the worst amount of body damage/bondo you discovered after you bought the car??

My 57 Ford Fairlane had the left fender sculpted in bondo to mimic the factory stamping (sort of a raised half round with a scallop in it) It was painted in primer when I got it and I knew it looked a little 'soft'. Sold it completely primered with all the trim taken off and holes plugged and sanded clean. Handed the guy the trim and he was stoked as I sold it in the "auto trader" and it was mostly pictures back then. My Mazda truck has rust holes through the single wall bed and its obviously bondod. I have raised portions of paint on that beast too, full of rust!