I like to do "detailing work" on the side for friends & family.
Years back, I detailed my Aunt's car. At the time, my 3 cousins were all under the age of 5. Not only was the car totally neglected outside, but the interior.....
!!!
It's understandable, trying to raise 3 kids that young, but WHAT A MESS! The "stuff" I found in the interior! And the smell!!!
I know this is a little different than the original question, but in my mind, that car was the worst car I had ever seen or had the unfortunate experience of driving to be detailed.