“D” Class properties are older, declining, potentially rapidly declining areas, characterized as bad/challenging neighborhoods, are older run down properties and potentially dangerous areas (war zones).

All this took about 2 weeks and still things were not final.At then end of deadline, thinking if this is causing so much trouble for simple application and with red flags in application he may cause more trouble when he will be in lease,  and told him that I cannot wait further go with his application and look for other candidate via e-mail and told him to pick up his initial deposit of $500 along with his application / documentation from my friend agent (where he dropped). 

I don't know about NY state, but I've checked out a few houses in NC that were flagged for demolition in three different cities. 

Not a red flag by any means, but certainly not IDEAL.

@Alejandro MagnoIn my previous post I included an image of my analysis which for some reason got flagged for removal.  

A Red Flag: I pulled up the parcel record and noticed some irregularities in the sales history.

Also in my area, a sheriff's deed serves as a flag that some mortgage(s) will no longer encumber the property.

But its a commercial property.There is a big red flag that you're paying too much for this property. 

A late paying rentersends up a red flag.

I am a big fan of threatening a BBB Complaint, which seems to create movement at levels above the loan officer, as that can be a huge red flag for higher ups at the main office.