The buildings underwent massive rehabs so they are easier to manage than the average c-class property. 

The second part of the problem is that there wasn't enough rebar in the slab and and probably a less than optimum mix of concrete.

One backdoor approach to buying a house at such a massive discount is to but a Non Performing Loan/Note  (NPL  or NPN).  

DO NOT take on these properties with existing tenants in place if you don't want them there.If you can't have a condition of the building being vacant before closing then factor in lost rents and possible damage to the property in your purchase price and exit strategy.One benefit to having someone there even with lost rent is you keep a tenant living there and the building from sustaining huge damage if it was totally vacant.I know some people that will let the tenant stay there for just enough time to rehab and fill the others.Eviction takes awhile so you should have started long before now.The voucher doesn't mean anything to you as the lease was with the prior owner.You would have to get with the case worker and the supervisor possibly.If an annual inspection has not been performed you might have massive repairs to get it up to passing.If the place is not habitable and section 8 deems it not fit for living they will tell the section 8 tenant to move or lose their voucher.Also if the property has been unstable or the area section 8 might take the property or building off it's approved section 8 voucher list.At this point you just have a holdover tenant that you should have tried to get out long ago.You have to look at tenancy laws in your area.It is a common mistake I see for investors to think that section 8 works the same way in a different area or that the landlord laws are close or the same to where they live or have been investing currently.This is far from the truth.

Potentially you could fill the crack with epoxy and put a new surface on the concrete.

Foreclosure is giving way to short sales and there are still a lot of properties that are deliquent by 6+ months which will probably end up on the short sale market and also there is a massive number of properties (reports say up to 1/3) under water.

Even paying the HML high interest I still free up a significant amount of income that is going to rent- which can go toward making a massive down payment to buy the home back from the LLC 9 and pay off my HML :).

He said the bathroom tub was leaking badly, and the concrete wasn't sealed, which should be the source of the problem.

I was really surprised because the neighborhood was amazing and the house only needed cosmetics on the inside and massive landscaping on the outside.I spent a few more hours and drove around more “high glam” popular neighborhoods and found quite a few more just like this – with the mysterious white stickers and ghostly appearances of an extreme lack of human care.

He had a frame made with expanded steel sheets (the diamond stuff) welded to the frame and set ancor bolts in the concrete slab and locks the cage over the AC unit when a property is vacant while working there.