In old houses I market new windows and exhaust fans because many older houses don't have them.  

Some of these my realtor and I have discussed, but a few we haven’t so these are great points.Do you have any thoughts on cast iron pipes?

., termites, busted pipes, mold.  

In the picture where you can see the gutter/white down spout, that at one time would tie into the cast iron (guessing its cast) pipe hidden in the picture behind the white down spout. 

@Johan Yang For older homes, you want to consider checking for lead-based paint, asbestos, tube wiring, lead pipes, etc.

For example, If the umbrella policy requires that you have a liability coverage with a $300,000 limit on your Homeowners policy, the Umbrella would start paying after the Homeowners Liability is exhausted in a claim. 

She let the oil tank run dry, so we had to heat the basement to keep the pipes from freezing. 

Turns out, the (month to month) tenant was out 5 months ago before a pipe burst and the city turned it off.

Not sure this was what you were going for, but I proactively remove any accesable galvanized supply pipes (replace with Pex)  or cast-iron drain pipes (install extra cleanouts) I replace all fixture shutoffs to quarter turn ones. 

Then put white pipe over it.