I suspect your condensation problem relates to heat escaping through the old roof and meeting the cold air. 

After graduating from the University of Delaware this past spring, I moved 20 minutes back to Wilmington, DE where I work full-time as an Aircraft Mechanic in the DE Air National Guard. 

I would like to own a chain of tiny house cottages/villages across the country for air Bnb or rent or own in some of the nicest places. 

My associate owns a rental property in Texas that is a SFH 4 bed 2 bath and rents out 2 of the rooms to long-term tenants while reserving the other 2 rooms for short-term Air BnB guests.

., That is a good idea, but unfortunately this airport is not like that, small town = one runway. not a whole lot of big industries in the area ( only a couple). my rentals are Student and full year round tenants, no Air bnb type rentals. i did actually aggressively looked into purchasing a B&B that was for sale a few years ago, but backed out of it, area does not attract enough people to warrant it. i am trying to start something that may bring people to the town, my recent thought this week was actually utilizing the airport with a helicopter site seeing/ hunting transport - currently looking into it, of course that would mean building a helicopter pad, this airport has the room bus does not even have that. thank you for that suggestion though, if i do the helicopter, that may be a service to add to it.

One of the items the inspector said to explore was the stove- it has a microwave above that was blowing air off the stove into the middle of the room, instead of up into the wall and out of the unit.

Both central heat and air system have been checked.

Fresh paint in a light neutral color and the place being super clean & not having an Odor (maybe put in air fresheners) & taking nice bright clean photos for the rental listing is the biggest bang for your buck in my opinion.

Do you replace the air filters monthly yourself or allow the tenants to do it.

Yeah, I thought of doing that credit for the central air but with the exterior work, first, the house looks really terrible, no curb appeal at all.