Let's run some made-up but realistic numbers.
$800 a month, $9600 a year gross
-Subtract 10% (being generous) for vacancy. We're down to $8640.
-Subtract 10% (again, generous, since this is a bad area) for management. Down to $7780.
-Subtract $4000 a year for maintenance and capex (imo, incredibly generous, assuming this is a standalone SFH). $3780 left.
-Subtract property taxes. Don't know these, but let's be really optimistic and say $1000 a year. $2780 remains.
-Subtract insurance. You might be able to get a cheap landlord policy for $600 a year or something, it'll depend on where you live (higher is likely, though). $2180.
So in a best-case scenario, you're going to make <$200 a month on this. Assuming you paid cash and don't have any mortgage interest to deal with. With a mortgage, you're negative cash flow every month.
Best case.
We haven't gotten into the oh-crap-my-tenants-are-making-meth or eviction costs or tenants sue you possibilities, of course. And we're not accounting for your time, because your property manager is going to call you for decisions on stuff and you're going to lie awake at night thinking about it, even if you never set foot in the place.
I mean, do what you want. I wouldn't buy it.
-W