@Paul Henning Cost per sf is a notoriously bad predictor of value, unless comparing nearly identical properties like two condos in the same building. 

Land use, zoning, and permits are notoriously strict in California, so having a big dream of what to do with big land may be kiboshed by zoning or ordinances. 

Some counties (like Philadelphia) are notoriously poor at serving the owner with notice of the sale.

AirDNA is notoriously bullish on their property estimates.

AirBNB provides some host coverage, but it is notorious for being hard to collect and it doesn't cover owner liability.2.

Others will use bathtubs for laundry or for cleaning out cooking equipment because they don't like the size of the sink.Married student housing is notorious for being infested with cockroaches and rodents for a reason, and it's not because the universities don't care. 

Two points.....1) ignore the 1% rule (do some research on here) and 2) Why buy in a super expensive city that's in a state that is notoriously landlord unfriendly?

Warranties are notorious for not delivering as promised.

As I explore my core 4 and look into different markets I am contemplating on a couple different places where the entry level is more do able to compound a strategy, and implement the notorious BRRR.

One notorious one is in the calculation of Net Operating Income (operating income minus operating expenses).