Though this is my 2nd deal, this represents a red flag (unknown as to what is in there and it's condition, the home is 110 years old) to me and among other smaller issues related to water stains in the unfinished basement (satisfactory) non working sump pump (can be replaced), water heater leaking (agent said will be replaced) , etc .. how should I approach this???

My building has two dormers that are clad in untreated wood, and I would like to seal or stain them, or open to other options. 

She made stove top popcorn constantly to the point where the ceiling & cabinets above the micro-wave exhaust became covered in a yellow greasy stain.

The general idea is to renovate the kitchen with new cabinet & counter top; Update all the restrooms; patch up all walls; remove pop-corn ceiling, repaint whole house; re-sand and re-stain all the hardwood floor; some plumbing work; install can lights in all rooms; move some lighting fixtures; add/move switches and wire for Ethernet.

One animal in a two-bedroom apartment can easily cause $2,000 in damages from torn/stained carpet, scratched doors, chewed trim, etc. $100 a month for 12 months is only $1,200.

I've been to a lot of closings around here & its not unusual to see people in pajama pants & baggy stained track pants, basketball shorts & t-shirts.

I mean painted over water staining.

You can always do a darker stain on the wood if you want to match the floors.  

I am rehabbing a house with pet urine stains throughout the upstairs subfloor.

Paint inside, and out, they've painted on the brick exterior and the new shed I put in just for them, they've ruined the carpet/vinyl and decided to rip it out thus they've stained up the hardwood floors, the kitchen and new appliances are toast, busted a new window, torn out and lost new screens, the bathroom WAS new, they've ran a leaking clothes washer and soaked the floor which is probably ruined, that leak has gone into the heating duct work and has pulled away from the furnace, they tore off every down spout which has resulted in what used to be a bone dry crawl space being wet, I cut the yard yesterday(when I saw all this), and they are three weeks behind on rent.Human trash is being kind...