Prices have jumped up pretty significantly the last few years; I had an addition done in 2021 just when lumber was starting to go berserk and I spent $100/sf *BUT* I use a lot of these contractors in my rental business and it wasn't a turnkey job - I did the electric, insulation, HVAC extensions, painting and trimwork.

I would like to know what all qualifies as completely clean here- Electrical wiring is normal and no unlicensed modifications - Structural inspection is also clean.Seller is ready to discount the price by ~20% from market plus the cost to repaint the whole house What are other questions to ask and things to consider in this scenario?

I even had two people claim to be licensed in certain areas that in fact they were not and could not even pull a permit... not to mention they were not even properly credentialed for major things like electrical and plumbing. 

HVAC, electrical, major plumbing, etc.I know for a fact there are a lot of people not following the ARS on that. $1,000 doesn't get you very far these days.

As soon as you open up drywall, frame new walls, redo electrical or plumbing your timeline and budget explodes.A good flip follows the same sequence as new construction:1.)

The home has a newer roofer (7 years old), New Furnace (2 years old), Newer Windows, and New Electrical.

Renovation PlanScope of Work:Convert 0.5 Bath to Full BathEstimated Cost: $7,500Details: Add shower or bathtub, update fixtures, ensure proper plumbing.Add Bedroom in BasementEstimated Cost: $15,000Details: Install egress window, insulate, add walls, flooring, and electrical work.Replace DeckEstimated Cost: $3,000Details: Replace existing 8'x10' deck with new one.General UpdatesEstimated Cost: $45,000Details: Update kitchen, bathrooms, flooring, paint, fixtures, and necessary repairs.Total Renovation Costs: $70,5004.

Now he says he needs to hire an engineer.

They messaged us immediately demanding "a full refund because your listing says you have electricity, but you do not!"

Learning the basics of electrical , plumbing , AC , painting etc will help you in this line of business which also save you a lot when you acquire your first home.This is how I got started , maintaining the rentals of my uncle  when I was your age.