My favorite is when GM placed one under the seat, but screwed down to the floor board, and sold it as a chassis van for carpet cleaning companies. GM would not allow the outfitters to remove them and relocate anywhere else so each time the carpet machine would splash water out it would corrode the module, it was not long and airbags would start blowing at red-lights, and some when you would step on the gas pedal.
My 04 new body thru 08 f-150s that I have owned (not sure of other model years) they mounted the fuel pump driver module on the frame cross member near the spare tire, the the aluminum backing would rot away. The new design used a rubber and plastic spacer which helped but still rotted out. I replaced mine, and installed a zip lock bag around and siliconed it shut.