Am I overlooking single family properties?

[Sam Munroe]

I am a new investor and have been solely looking for duplex properties. I see a lot of nice single family homes for sale and often see investors talking about their portfolios of single family homes. When I run the numbers, I often see little or negative returns on these SF properties. Am I looking at them the wrong way? I'm evaluating against the 1% rule and with utilities and taxes, most of them are negative. Am I missing something? What factors or metrics should I be looking at? 

Single or Duplex Requirements I'm using:

150k or less

Turnkey 

C Neighborhood or better