I'd be looking for a mix of homeowners and renters, not a purely rental neighborhood.Don't get too caught up on the A/B/C/D "class" and focus more on the economics of the real estate market in each particularly neighborhood. 

That market is notoriously susceptible to broader market/economic fluctuations.

That's not to say that there isn't any opportunity, but you'll need to do a bit more digging into how the deal can withstand a second shutdown or any other sort of economic disaster.

So I view those as interconnected concerns.Bad debt is much more specific to your property and area.Depending on your area and property class, I'd get nervous to underwrite anything less than 10% economic vacancy (physical + other).

Population, Economic diversity, Average income, Average DOM for the area.

Great economic dynamics here.   

Based on that information, I would think San Diego would be less impacted economically than most areas of the country. 

I was too young to remember the 2008 mortgage crisis, but it seems as if a similar situation happens most investors will be wiped out if banks began calling loans.How much money in reserves is necessary (in terms of months/years)?

@Simrun Mirchandani If you are able to make your payments and your situation has not changed due to the current crisis, you should make your payments.

You also may want to have up to 6 months of reserves for each property in case of an unexpected capital expenditure or economic downturn.