Reality is every group of humans has some bad actors.   

Additionally, there are no laws stating a dwelling must provide appliances.

I contacted the Humane Society and the officer told me the dog was being neglected and abused. 

Relevent text:The owner of a dwelling is required to post a notice which is constructed of durable material and which is no smaller than 20 square inches in size listing the owner’s name, address and telephone number if he/she does not live in the dwelling or have a manager living in the dwelling.

You can screen well, but as long as the human element is there, you could run into anything. 

The zoning key words you will want to look for are "Accessory Dwelling" or "Principal Building".

Previous insurance company doesn't want to insure the property anymore because the main dwelling is empty. 

Which makes me wonder why here in Los Angeles there is an extreme housing shortage, rents are going through the roof, the state recently passed an law making Accessory Dwelling Units easier to build in an effort to mitigate the the housing shortage, property values are at a level at or above the housing bubble peak. 

Make sure it’s a dwelling policy and not a homeowners policy otherwise if you rent out your place you’ll void your insurance

So if a dwelling cost on average 20k to bring to average condition the market will discount that property much higher then 20k allowing the frugal and knowledge rehabber immediate equity.