The worst roads I ever drove on were on the big island of Hawaii, particularly the road to the prison. I was just sight-seeing and wanted to go back there to see it, but got about 3 miles in at 5 mph (as fast as you could go without being thrown out of the car), turned around and went back to the main road that encircles the island. Unbelievable.
The rental car companies forbid you to go across Saddleback Road, the one that goes between the volcanos in the middle of the island. I guess they got tired of spending money to fix suspension systems on the rentals.