Regarding Floor 3 leak, I am entertaining a full roof replacement but may Karnak myself first since that leak could not be reproduced on my test and appeared after a heavy rainfull. water ran along a joist. 

I was looking at these areas as well as they were cheaper than buying in Rockville and also appeared to have some decent homes.If getting the ADU would be tough in general and renting by the unit in those areas would also be challenging I may need to rethink my strategy.I am doing this as a first time MD homebuyer and looking at my options to rent a portion of the home.

Get inside photos of the property and see what it looks like and if it appears that someone is getting ready to move?

If so, then finding tenants doesn't appear to be a problem.  

For numerous reasons, this strategy is not anywhere near as simple as it appears, and the risk of default problems can be quite high if the seller is inexperienced or unknowledgeable.    

Some of the assumptions appear likely as 7 inspections out of 7 all revealing major issues is not impossible, but at best unlikely.The question really is the severity of the problems that the inspection revealed.

For example, the tenants in my house hack pay the equivalent of the interest on the mortgage.

What you've written is the equivalent of the abused woman who stays with the abusive man because he'll change. 

I'm surprised that someone who recognizes the illegal importation of often unvetted individuals would seek to find yet another way to fleece the taxpayers.To answer your question, though, it would appear that the money being made is passing through non-profit agencies who then make the decision where to house them. 

Mike- I see a lot of properties available in Hagerstown (duplexes) that appear to provide decent cash flow.