It looks like rotted wood with paint over it.

I've often thought it would be cool to take cheap dry cabins put a water tank and composting toilet if you wanted to own something outright.

When someone does try to use it, there may be technical problems, dry ink, etc.

You might see a failing foundation, water intrusion, rotted joists, ancient water / waste lines and who knows how many other red flags.In the attic, I look for knob & tube wiring, missing or insufficient insulation, leaks, crumbling chimneys, etc.To have both of those areas off limits would be an absolute deal breaker for me - and shame on your Realtor, who is supposed to be your fiduciary! 

Could be just rotting subfloor but I don’t want to take any chances thanks!

We have one rental with the same setup and the tenants appreciate the ability to store things down there (assuming it remains dry) but woudl not want to use it for anything else. 

A sump pump would almost be mandatory, on top of dry locking and proper grading.This works great in college towns where renting by the bedroom is linear.

12 years ago - wood laminate floating in dry areas and tile in wet areas.Today - what @Billy Daniel said!

Heavy spider infestations can be a sign of water damage or rot.

I positioned the door on the ground and then tilted it up into place for a "dry fit".