For example, I know a guy that only buys multifamily, but comes across good single family deals all the time.I'm surprised by the people that turn to Wholesalers instead of realtors.  

First off you have to identify what kind of investing are you looking to do (single families, apartment complexes, etc.). 

I currently have 5 single family homes right now.

So check the median income per person, unemployment, single mother prevalence, racial diversity, vacant property rates and property and violent crime.

Hello,Our duplex is insured as a single family home.

The triplex is not our current residence; we currently reside in a 350k single family house that is no where close to be paid off as we have only stayed here for six years thus far.

To put is simply - it's EXTREMELY easy to get around in the city.Another think to think about for Single Family properties is there is an ordinance that says no more than 3 non-related people can live in a house together.  

We have the goal to focus on flipping single family homes until we build enough cash to buy large building with 4+ units. 

There's a zombie duplex (with an additional trashed single wide) that I'm eyeing if I can get it for a song (cause let me tell you, this place is what nightmares are made of, but I'm a glutton for punishment).

There is no single one important number for us.