A prime example of the junky cars are the scrap metal/junk collectors here in Chicago.

Generally, these are pick up trucks, at least 15-20 years old that have "modified" the cargo bed of the pick up truck to be able to stack 10 feet of old bicycles,bath tubs,sinks,pipes,..etc on the back. They cruise around the back alleys of the city and pick up any old bit of metal/junk they can find and take it to the scrap yard. These trucks arer literally held together with wire and duct tape.

I am sure it does vary from state to state but here in Illinois you see some pretty crazy stuff.A policemen may pull you over for a broken brakelight or similar but there are vehicles driving around here that you do not want to be anywhere near in traffic should they ever need to stop suddenly.