You rock

So, instead of evicting them to do a rehab, I lowered their rent a bit, consider it my band-aid house I will be working on forever, and they love me and all is well.

Typical the lower class the area, the higher the returns, and in Philadelphia I believe the sweet spot is in B and C class neighborhoods. 

If you try to use a paint brush/roller it will feel in the very small texture on the sheet rock which is what makes it noticeable.

Most tenants in B and C class properties don't care that much.

His previous experience includes purchasing buildings (like an old body shop) and sand blasting the interior, polishing the floors, redoing some sheet rock and leasing to tech companies looking for an open floor plan.

I've been out of commercial construction for a while now, so I may be mis-remembering, but here in Kansas City you could get new asphalt pavement laid (including base rock/fine grading) for $50 to $70/SQ ($5.5 to $7.5/sf).   

Generally speaking rock stars know rock stars....so if you can interview and find one of those you can get to others.    

But Detroit might still be the place to go today if you want to buy real estate at rock-bottom prices.According to the book Investing the Templeton Way, people who bought farmland on the courthouse steps at the depth of The Great Depression for the 50 cents of back taxes the farmer couldn't afford to pay made out well in the decades after The Great Depression.

Most of the rock bottom "for advertising purposes" stuff you see online has VERY conservative assumptions, with everything being 100% vanilla, which basically means only 1 in 50 can get what they advertise.