How do you define a "B Location"?

[Jared Viernes]

I have been listening to show 61 with Ben Leybovich and he said something that rang loudly for me. Paraphrasing he basically said you need to buy a C property in a B location and fix it up to a B property to bring in better rates and tenants. I am moving soon and plan on becoming an expert in an area nearby where I will live by driving for dollars, attending every open house and learning that particular market in any way I can. However, I have yet to actually decide on the location yet. I want to know how you would define a "B Location"? What tools do you use to help you to identify your criteria for B location across a zip code? I would like to define a particular zip code and become an expert there. Any other advice in figuring out first what market to become an expert in is welcome. Thank you all for your time and input.