As a former technician, I saw my share of eye popping sites in customer vehicles. During my 10 years as a tech, I came across live and dead animals, unsecured guns, open containers of booze, narcotics (dealer weight), and pornography (an entire van full). I always give the following advice regarding taking your car in for service: if there is anything in your car that you would not want others to access, see, or read, get it out of there before you take it into the shop. With the number of electronic modules and proliferation of wiring in modern vehicles, technicians often need to access these by going through the trunk, glove box, the center console, and under seats.
That said, there are two cars that came through my stall that still stand out for me to this day.
First was an Olds Delta 88 owned by a person who had eating and hoarding issues. When the car came in the interior was literally filled with garbage. The repair I needed to do on the car required removing the seats and pulling up the carpet. To get to the carpet, the garbage needed to be removed. I had the service writer talk to the customer and he agreed to pay for me to remove the garbage from the car's interior. I ended up filling two 55 gallon cans with the garbage from the inside of the car, which also included a partially mummified rat carcass.
The second was a car owned by a government law enforcement agency. The person who brought the car in failed to check the trunk to see if it had been cleared of any law enforcement equipment. The repair I needed to do required getting into the trunk, which was filled with enough weapons and tactical gear to equip a small fire team.