One thing I do on every inspection, because I have long arms and reach eight feet, is raise my flashlight up parallel to ceiling height and see what I can see in the drywall. Any previous repair will be revealed, unless they are as good as I am at doing drywall... (yes, that was a bit of a toot on my horn).
And my practice is always revealing when problems are hidden.
I saw this from across the room.
When leaks require drywall repairs, I will see them from across the room.
When leaks only stain the drywall that needs to be primed and painted, I will see that from across the room.
Do you know what you are looking at here?
That is the pattern created by the material at the bottom of a can of spray KILZ.
KILZ is a stain-blocking primer. It is good stuff. It seals the brown stains that leaks develop on drywall. You can paint those stains 40 times and unless you seal them back with a stain blocker first they will continue to come back.
How do I know this is the bottom of the can? C'mon! Experience! I have used the stuff!
There is another way to see KILZ. If the KILZ is not itself sealed back with a second layer of flat paint, it will itself bleed through a single coat of paint and is shiny! Flipper doesn't know that! Yeah, this same guy. And I already told you how I know about KILZ, and the shiny bleed through...
But what's above this repaired spot? An old stone fireplace and hearth. And new hardwood flooring. Nothing significant that would leak.
But it's still wet! 17% moisture is not dry!
Where's the moisture coming from? This is a repair, and the stain is localized. So it must be a one-time leak.
Could it be from here? We know that plumbing wasn't done properly. And we couldn't see under the tub. So I filled the tub up and let it drain. No leaking. It might be that the tub leaked a couple of days earlier and it has been repaired.
Could it be the fireplace? In the basement wall, under the fireplace, there is a cavity in the foundation wall used to help support the chimney's weight. Drywall and book shelves were put in the cavity. All around the floor molding and up the drywall the moisture registered over 30%. That is active moisture intrusion!
But is that getting inward to the basement ceiling and under the hardwood flooring? I would doubt it. The moisture would have a more dispersed pattern, and would probably be moist all over the basement ceiling.
I think it was a leak. BUT THAT BASEMENT WALL IS STILL A HUGE PROBLEM! PROBABLY A DIFFERENT ONE!
My recommendation: people sometimes try to hide problems. Especially flippers! While I am not necessarily looking to see if they are hiding something, disclosure is not something required in Virginia and I must be diligent in trying to find things. Like seeing the clue above! Again, when you hire a home inspector, get a bull dog with experience. They pay off in the end!