TOPIC: What's this from?

Alright boys, here is a fresh pic from a home inspection today. This is the side of a gas pack up in the attic. You tell me what you think. I told the lady she needs to have it serviced and looked over, before she buys!

That appears to be combustion gas or heated air leaking out and condensing on the wall surface  causing the rust. I can't tell the orientation of the unit from the pics, but that is my opinion of what is happening.

Without seeing the whole view of furnace or what that section is it is hard to tell. Not sure where the exhaust vent is but moisture can cause a lot of damage. Yes refer out to be further inspected.

This absolutely should have been called out as you say you did! It is evident that the system is rusting out, which does reek of a moisture problem! But even more important, if this is a combustible system, the weakening of the walls will probably eventually lead to carbon monoxide issues as well; and with this system being in the attic, where many people are going to forget that it is even there, there is a dangerous possibility of unawareness when holes in the system begin to form. Recommending further evaluation was the Right On thing to do! 

Condensation is common in those units in attic spaces.

What are they doing with one of those metal shower stalls in the attic??

Yes, condensation is common when the system is found in the attic, and as we plainly see, breakdown does develop because of it.

It's not clearly visible Jay, but in the lower photo, I believe that I can make out a water heater that appears to be sitting in the pan.