About 30 years ago I used to steer an old mack pulling a even older end dump for a demolition operation, the Mack looked half decent, just not shiny, but washed when it needed it. the trailer looked rough, demolition trailers do. Got red lit at a scale, An older experienced DOT and a fresh rookie came out of the coop, the older guy came over, looked at my papers and grinned, when he saw the rookie come back with a creeper and his ticket book, The "kid" was out for tickets, but the experienced hand said , leave the creeper , look at the slacks, they are clean , the tractor tires are even tread, the lights all work. there are no shiny demo trucks.
Actually I have found that DOT guys seem to have an extra sense about junkers, they often stop the too shiny rigs, and the never washed ones most, they seem to leave lowbeds alone unless they are obviously wrong.