It takes a look into how the economy and politics actually worked through a cast of characters who are the scientists, planners, economist, ect that have the responsibility of trying to make the blended politically and economic engines work.

If you have old galvanized and cast iron piping, old knob and tube wiring, old boiler system or a foundation that is failing, then run away.

Because of what I learned on this site and pod casts, and the people who I have met through the "unofficial" BP meet ups: I successfully negotiated $100k off of asking, got substantial seller financing, got the seller to agree to demo "non-code" compliant work and do expensive sewer lateral work. 

You cast an incredibly bigoted sweeping indictment over an entire group of people based off your own skewed ideology.

The drain cleaner snakes or jets the line and rarely are they able to see the items flowing past.Also in some cases it's a combination, it could be an old cast iron pipe with a rough inside surface full of rust, which started to act like velcro to things that flows past, or a slight settlement causing a belly, which again impedes the flow, then the tenant pours down grease, pasta and bean, well, you get the idea.Most of the time you end up eating the cost especially if the plumber can't tell you anything.Now, you mentioned that the clog caused water to back up to a vacant unit next door. 

I am slightly concerned about the age of the house and what lies under all the sheet rock (possibly cast iron plumbing, old electrical, etc...) and don't want to be held responsible for someones child dying due to my neglect of DD and the house burning down.

You will find resources here from blogs to pod casts and forums.

If I am certain that it isn't my problem (ie collapsed drain line or corroded and scaled cast iron) then I pay for the first unclog on a drain and the tenant pays for subsequent unclogs of that same drain.

I would say that Joe Gore has just reestablished an account under another name but that may be casting Joe Gore in a bad light, which I would previously consider an impossibility

Here are a few items they highlighted - repaint concrete sidewalk which had been previously painted and now chipping and replace a cast iron plumbing stack, which is functioning PERFECTLY, only because it is STARTING to barnacle.