Filthy trashed rentals?

I helped some family clean a rental house that had been trashed over the time of 1 1/2 year. I was so smelly, like cigarettes, dirt, and more dirt. This place was nearly brand new when they moved in 1 1/2 yrs. There had been a "walk thru" 6 months after they moved in and it seemed ok. I spent 6 hours min. on just the refrig/freezer and stove (not self cleaning). Goof Off and Krud Kutter are great cleaning solvents. I also used one of those steamers by Shark to get crud out of cracks etc. Looking for advice from those who have cleaned up after such dirty irresponsible people. Oven OFF 3x and still need some work.