Just the nature of the business.  

For the seller WHO they sell to might be financial only in nature or might have an emotional component also.

Once you have practiced it a few times it will become second nature to you and you will be able to do it allot quicker, more efficiently and accurately. 

The current heating system is natural gas with old cast iron hydronic radiators.  

You also mentioned not finding wholesale deals on MLS, which makes perfect sense since by their nature they're off market deals and wouldn't be on MLS.

However, you cannot ask the nature of the disability or reason for needing an emotional support service animal.Service animal or not, you can also require vet records now and annually that the animal is up to date on all its shots.Also to keep in mind, although you can't charge a pet deposit for the service dog. 

am I ready to tackle a turnaround project of this nature?  

Nature is beautiful, comforting, relaxing, and soothing to my soul. 

If you are smelling something such as a natural gas leak, that is not something picked up by a CO detector (that I'm aware of) because that's pre-combustion.  

Maybe they have substantial savings from an inheritance or settlement and they draw from that to supplement their monthly income?