You can build up goodwill sending grocery cards at Christmas, having a mini fridge to rush over the moment there is a problem, giving rent credits, etc. and it will mean LESS THAN ZERO as soon as you have a late fee you expect them to pay, a pet that you cannot approve, anytime the rent goes up, telling them they can't paint the walls and ceiling the color they want... then you are the scumbag landlord.

And for someone to get so much of the fruits of my labor seems like an injustice to myself. does that help paint the picture a bit better? 

Always, get the paint updated to a relevant color and then take first class photos.

Which isn't necessarily a bad thing and should pay for itself, but you are ripping your guests off if 8 people feel crammed and there isn't enough plates and room at the table for them all to eat together. 

THATS how you add the value, by repairing the defects, kicking out squatters, painting over spraypaint etc.

(sigh)In the case of subto especially there are many risks for the seller that usually outweigh the benefits by a lot: such as messing up their DTI ratio, may not qualify to get another loan, and in worst case scenarios if the buyer rips the rents and doesn't pay the mortgage: wrecking their credit, forcing them to sue the buyer or foreclose on the buyer, and effecting their ability to even rent a home in the next 7 years.

Interior and Exterior Upgrades; Modern Appliances, Tiling, paint, etc...What was the outcome?

. : $2,347-Paint, all new doors, plumbing fixtures, drywall work, garbage disposal, carpet, bathtub: $3,934-Labor: $7,976The previous owner did not do any updates to this unit for the last 25 years!

We will be ripping it out and replacing.

We did a light rehab which included paint, carpet, fixtures, turf in the backyard, and a new roof.