There comes a point where you just need to bite the bullet, as it were. Try this analogy:
To guys buy the same model car in 1990. One of them changes the oil on a regular basis, keeps it washed, never eats in it, never races the engine, etc, (you know, all that stuff we all feel guilty about!) The other guy is more typical, not changing the oil until the oil light comes on on his dashboard, NEVER washing the car, leaving old banana peels in the back seat, and leaving the windows down when it rains. He takes it off road, and never gets a tune up or changes the tires.
Same identical cars when they came off the assembly line, but 5 years later, the one car is worth a whole lot more than the other, and to make the second car worth anything close to the first, you would have to spend more money than the car would be worth.
My suggestion is to sell the house as is for whatever you can get for it. If there are some inexpensive things you can do, like mow the lawn, really CLEAN the place, get rid of the clutter, go for it. I wouldn't bother trying to "fix" the place because chances are the buyer will have other ideas in mind anyway and just tear your repairs out.