Seeing as the walls are about 7 inches thick of 4 different layers of wood, is there much need to insulate?

He had dropped out of college and bought up every spare inch of space and converted it into fully furnished apartments that he rented to kids for ungodly amounts of money that their parents happily shelled out every month.

So I sprayed a soaking layer of vinegar on every square inch of the plywood 2nd story floor & stairs, which helped but didn't eliminate the odor.

Also the switch plate was almost 1/2 inch off the wall.

@Greg Mitchell  I sometimes "give an inch" for tenants who have an otherwise good history with me but as a general rule, it's usually best to stick to the rental agreement. 

We usually replace the refrigerator and 30 inch basic gas stove every 5 years.

I'm looking at a multi detached home and it looks like the foundation has shifted on one side of the house causing back porch, part of the kitchen, and door jamb to shift about 3 inches down, a hole in the wall in an upstairs bedroom, mold in the basement, and strain on the basement wal-out awning.

There used to be an inch it two porch (cement just raised) it now has a gradual slope like a small ramp.

If so, that should have been a red flag.If you're in an especially low-rent market (and it sounds like you are) and you're concerned a 12 month lease will make you less competitive, you might consider using an inexpensive loss-leader like a "free 40-inch TV" with a 12 month lease as an incentive to sign.Just remember the price of the TV when you need to go after the tenant for a broken lease.

That might take 1 1/2 inch at max which isnt noticeable.