Then you say there’s a brothel a few doors down.

While I can imagine some cities might be against "boarding houses" or enforce their "brothel law" I can't imagine too many cities would be supportive of it. 

Most cities do not allow "boarding houses" and/or have a "no brothel" law. 

was this once a brothel?""

C3 zoning in Atlanta is considered "commercial-residential" so there's nothing an underwriter would have heart burn over.Once you own the building and the land next to it, your use, unless specified in your mortgage note (or unless it's illegal like a brothel or a meth lab) is up to you. 

I suspect that almost perfect applicant was trying to rent multiple house to run a network of brothels.

Tim is a great resource on lending and mortgage information and has been a great help to me.To see my project search Investa-brothel on bigger pockets....

I was informed by a neighbor that as recently as a couple years ago, the one house was basically a brothel, it's been cleaned up once the neighbors got the police involved but I imagine the tenants aren't the best.   

... or you could just open a brothel.

Banks,car manufactures what's next your local Outback steak house or how about that brothel down the street I'm sure that would help the economy.