Challenges?

It is a tough buy and hole RE market everywhere but markets like San Francisco are particularly challenging in the short term due to the poor cash flow (negative cash flow).  

A free property is great... but if you find a deal good enough to BRRR (which can prove challenging) take that profit and invest it into a revenue generating activity.

Labor shortages have hit that industry just like everything else, so finding reliable, trustworthy, quality cleaners is a challenge everyone is facing.

It's challenging to distinguish between genuine advice and potential scams in the vast sea of information available online.

@Robert Frazier Land entitlements are difficult and seems you've now been exposed to appeals and design professional challenges.

If I were to go this route I would clearly identify each of these risks individually, understand how the Govt would potentially challenge each of them and then assess in your particular fact pattern how you would effectively rebut a challenge to each. 

If you're challenged for space, get a stackable....

If it is very rural having contractors and completing on time and accurate numbers can be challenging.

@Elliot B.I doubt a energy meter based on airflow, heat - etc - of any variety - would hold up if challenged in a court of law -