One of the true joys of being a new homeowner is discovering unexpected problems during projects or when getting "minor" repairs done. The previous owner apparently fashioned himself a DIY king.
Painting the ceilings and removing the AC vent- Oh shit, there's mold in the ductwork.
Replacing a gfci outlet- Well, the one that tripped is actually on the ceiling, where it's not meant to be and by the way, your entire breaker panel, and even the box itself is completely fucked because he cut a hole in it for this random power source. Also, it appears all of your outlets are backstabbed so they'll probably start giving out soon, because they're old and they used the wrong gauge wire.
Gas leak that is fortunately just within the oven itself- By the way, your water heater, despite being only 2 years old, is a disaster waiting to happen because it was installed by a moron.
Somehow, much of this was undiscovered during the inspection, or chalked up to a bunch of little things that you can slowly fix over time. And I'm sure there is some upsell by the repair people who have been out here. But other than the HVAC unit, the universal, and immediate, response to anything they've looked at is pretty much "Wow, uhhhh.... that's interesting."