Expanding on the @Shaun Reilly  post, in NC you can provide some peripheral real estate services (but not the actual leasing) and not need a broker's license.

While there are many other factors for making an area "highly desirable" or "undesirable" generally you should know the trends of things that matter to the tenants such as: schools, crime, local economic developments, companies relocating in or out of your area.According to latest stats, it appears home ownership is at lowest levels in way long, hence you can assume (pending the fannie mae 3% downpayment upcoming thing) that lots will rent.

On the positive side, all of the interior walls are concrete block which limits peripheral damage when shooting occur inside the buildings or tenants set their units on fire. 

A house is a product, and like all products some are undesirable.

Also, from what I see, distressed properties are in an undesirable location for me as a single woman.

Look for things that will make it undesirable to future tenants like busy roads, no yard, no parking, quirky layouts, etc. 

I have spent many evenings watching them transform a property from undesirable to gorgeous.

It was making the place undesirable in and of itself.I'm someone who tries to look at the long-term picture. 

Or do the gutter screens cause other issues that make them undesirable?

Having a high threshold for pain as well as dealing with undesirable circumstances (two things all the Jackass guys seem to embrace) no doubt comes in handy as a landlord.