BTL Property in WNY

There is a wealth of property built between 1900 and 1940 in the Northern cities in the State of New York all for sale between 0 and $40000. There are a number of UK agencies who can supply these properties and advertise a steady supply for a fee, "having checked them out, surveyed them and found ready tenants". These properties are advertised at various net yields of between 15% and 30%.
All statistical information available reveals that indeed WNY is as good a place as any in the US to invest in property. These cities had their 2009 "Detroit" moment in the previous two recessions and the rebuilding and redevelopment of the three cities Buffalo, Rochester and Syracuse is well under way. These bottom of the market properties have not really suffered in the recent property crash as the values were pretty well at the bottom to start with.
There is an abundance of potential tenants, pretty much all on the equivalent of Social Security, to fill these bottom end properties. The stock comprises of 1, 2 and 3 family homes of one or two stories and typical US architectural style. The age of the properties means that however good the condition there is a fairly large ongoing maintenance requirement. The climate which is hot in summer and severe in winter adds to this problem.