Here's a possibility: prior to the hammer, owner sold the property (actual cure) or provided evidence of an upcoming settlement and lender agreed to it (enforceable promise to cure)

Everybody in law enforcement has the same  problem as the rest of us, in spades.

I'm curious as to how clauses or terminations of the lease are enforced if its strictly verbal. 

There is no statutory rule enforcing this, but it's normally good advice.

Did I know anything about construction, zoning, code enforcement, etc?

Do you charge and how much.Acceptable Vacancy Rate - we own a reasonable # of doors in the city of Milwaukee - not great areas but not horrible either.Thanks in advance Rent is due on the 1st and late on the 5th, we charge $100 late fee and we enforce it.

For your SFH and Multis it is really hard to enforce and track.

How does the IRS define the boundaries of material participation and how stringent are they in enforcing these rules?

Enforce the late fees every time to incentivize on time payments.

It was pretty hard to find properties where the numbers and landlord laws made sense which is what ultimately led me to investing in Columbus, OH.Not to mention the upcoming legislation on the November ballot that can really hinder your returns from rental properties.