It's not as simple as homes that were burned being rebuilt and original owners returning to them.

Most suburban cities have VERY limited lots and most of those are zoned R-1, meaning only a single-unit house can be built.In the City of Detroit, it's cheaper to buy one and rehab than build!

They also tend to offer good cash flow relative to their cost, especially in areas with high demand for affordable housing.

I interact with first time house hackers / seasoned investors on a daily basis.

You're just making profits for the lender.You could also sell #2 if you bought off too much house. 

I have done quite a few different things, one of the best to find out who is doing the most volume is go onto good and search for the "we buy houses companies" in the area you are looking to invest.

On a daily basis I get questions from investors/property owners about the rental rate for their rental property.

Quote from @Pearse Cafiero: You want to borrow money to buy a house, but you don't have the downpayment.

For example, houses where the homeowner needs help and may consider selling to me. 

We have been working in the affordable housing space for some time, and this allowed us to partner with the local community and provide a housing solution they need as their city continues to expand with new jobs they are successfully bringing to town.