It's also important to know that unpaid rent is substantially higher with multi-family tenants with only 76% of those tenants paying their rent on time.  

Even then, the "substantial involvement" requirement in the field might not match what you are doing. 

If the home is on good enough condition to get by the banks appraiser then there is a good chance you won't be buying at a substantially reduced price.

Typically for a rent increase that substantial you either have to already be well below market rents or add a bedroom or do a significant remodel - like updating an ugly kitchen. 

Also, wanted to clarify if the property that you're interested in buying is residential or commercial as these may require substantially different processes.

In July 2021 we learned there is an active lawsuit tied to our property where our seller is suing the previous owner regarding substantial driveway grading and basement water flooding issues that were not properly disclosed to us during the purchase.

I found a duplex in a great neighborhood that needs substantial repairs.

@Bobby Larsen While fundamentals might play a part in the substantial rent growth that's being realized in many markets throughout the country, it is my belief that the two (2) biggest factors are inflation and a lack of rent growth in 2020 due to uncertainty. 

If the market regresses substantially and if I was forced to reduce rents, I could still be making a tiny, undesirable cash over cash return.

You can expand your subject-matter expertise, but you become a risk factor when you try operating a substantially different asset.There have been cases and projects that seemed lucrative but had to turn down because it isn't my area of law.