Side note; normally I would never give out the address to a buyer without having it under contract already, but at this point I had already 99% decided I wasn't going to make a dime on this deal, so I figured no harm, no foul. 

That's such a foul word to put on this forum - I'm surprised the admin hasn't banned you! 

Essentially you setup your contract for a "no harm no foul scenario".

If the occasional litter box odor is strong, usually a quiet word to the tenant is all that is required.If they are non-responsive, it's a good bet there are other issues too, and the pets are the least of your problems.PS, although I am an animal lover, and do significant rescue and fundraising for animals, I don't allow the four breeds that my insurance company doesn't allow:German Shepherds, Rottweilers, Pit Bills and Dobermans.

Old shrubs make a house look old, new shrubs make a house look new.Tree low hanging tree branchesRun a dehumidifier in basementRemove cars from driveway, garage, and front streetMake sure sump pumps are in working orderHave drains professionally cleaned preventivelyTake down and put away all personal pictures, and any political, religious, or sports references.Professionally clean carpets.Make sure there are no odors, whether from pets, smoking, or cooking etc.Paint the entire interior with neutral colors, doesn't have to be white (snow blind white not recommended), but subdued earth tones work.Have heat or air conditioning on but set at moderate level, should not be too hot or too cold.Keep electric turned on, water too but caution for freeze damage and leaks in vacant houses.

Does it have pet odor, road noise, old paint, divided floor plan, bad street, evil spirits, etc.?

A neighborhood with a bad reputation, a salvage yard down the street that you have to drive past, being near an airport, could have odors from some factory a mile away under certain weather conditions that are common, these are EO factors you need to assess, as you say, build in more potential profit as you may end up giving more away.

If an investor cries foul and they take legal action or call an obligation, this, coming under the management issues of your operation should not be cause for your lender to get cold feet and bail on you too.

If there is no ventilation, adding a vent that turns on with the light could be a huge help in limiting moisture levels in a bathroom, if nothing else it will pull fresh air into the bathroom and help get rid of any odors.  

Many are not even known due to some foul up in the system or simply the offender neglected to register.