I like this one especially the creating a business partThe failure rate for persons who start business's for intent and focus of making $ is astronomically high.  

There should be mechanism to minimize duplicate or a question that's not having too much context. 

Some specific examples include careless installation of vinyl flooring in our kitchen, resulting in irreparable damage; leaving an exposed nail in remodeled kitchen cabinetry that scratched our new range; installation of bathroom sinks with improper plumbing connections; and multiple instances of failure to remove cigarette butts, food trash, and construction waste from our property.

If they refuse to pay and you installed what was quoted in a workmanlike manner then you file a mechanics lien on the property.

Mike thinks 15% of rent would cover vacancy, maintenance/cap ex, misc (missed payments, asset protection (actually I am not surehebelieves in asset protection), utilities from property failure such as slab leak).  

Structural, roof, mechanicals, cosmetic? 

More specifics - the main issue is failure to include the lien holder in the foreclosure suit (the State of Maryland was named, but not the MD Dept of Health). 

Apprenticeship is still the best learning mechanism. 5.

Nice wishful  thinking but if you approach real estate investing thinking it's going to be a completely passive endeavor, then your chances of failure will be much greater. 

Part of growing is recognizing our own failures, not shifting the blame to others, even when its really easy to see their faults.