We cleaned and repaired my mom's house a couple years ago before selling it:
Fixing Up The Dallesport House
She had smoked in the house for 20+ years (nicotine stains were running down the walls), didn't keep up with any maintenance, and just generally hoarded and trashed the place. It was dirty, smelly, and disgusting. I considered selling it as-is, but we wouldn't have gotten anything for it in the state it was in.
So, we spent about $6000 on basic repairs. We removed the filthy popcorn ceilings, repainted the house inside and out, fixed all the leaky faucets and toilets, and installed new (cheap) carpet. We "remodeled" the bathrooms using the cheapest materials we could find (peel and stick floor tiles, cheap mirrors and towel bars, etc.), but it "looked" new. I also replaced all of the light fixtures and electrical outlets, had a cracked window replaced, and replaced the water heater. We painted the kitchen cabinets and added some cheap chrome handles. Despite all of the inexpensive materials we used, everything looked and smelled new when we were done. It's funny what new paint and a few shiny handles can do for a place.
I'm guessing we got $50-75K more than we would have received in as-is condition.
We did have to fix a few minor things before we sold it, like splash blocks for the downspouts, and painting the shed. They asked for more updates like a new header for the garage door and installing a heat pump, but those were out of our budget. We declined, they bought it anyway.