You will also want to search Zillow, Google, and the county clerk records of the county you are looking in.Google and the County Clerk's office will help you see if there are/were any violations as well as well as sheriff sales. 

For example, I'd like to see the status of permits, inspections, violations, zoning issues, etc.

As far as I can tell, many are illegal rentals that violate HOA rules, zoning codes or both. 

We never heard about this conversation...A month later we get a violation letter from the township stating that our wall was not structurally sound and we needed to get an engineer to evaluate its soundness and if needed, remediate it. 

Don't put them on utility poles as that is a violation in nearly every city. 

Typically an actual sale, land contract, an option or a lease longer than three years will all violate the due on sale clause. 

Moral of the story, majority of the pro-sub 2 and wrap transactions tend to overlook all the other violations that are committed in the sub 2 process.  

Eviction laws give landlords quick, simple, and fairly inexpensive methods to remove tenants who have failed to pay rent, otherwise violated agreements in the lease, or remain in the leased real property for longer than the landlord has authorized.

Violations can cause penalties.

One of the list that I am using is an active code violations list.