Negotiate what you can. Nevertheless, you are not buying a new boat you are expecting to be perfect.
This is good general guidance. For some reason, these threads immediately devolve into hard-line stances that assume the other person is a total jerk which is often counterproductive to getting a good deal. Many (not all) owners have fond memories of ownership and are happy to see a friendly face taking the reins.
Assuming the used boat is, well, used, you won't be getting a full repair credit for most items. Sure, you have a right to expect bilge pumps and nav lights are operational and can request a full credit or repair, but many items are simply old and partially inoperable - maybe a burner on a stove or gauge isn't operable or some of the instrument lights are out. Maybe I'm a pushover, but my general rule is if something was advertised but is found to be end of life and needs replacement, I'll assume half the replacement cost for a new item. There is no practical way to do that unless I have the repair done post purchase.
There are exceptions. Anything electronic that was represented needs to work as expected. Many chart plotters and radar were never setup properly (eg vessel icon is at a 10-degree angle so vessel "crabs" along screen). Chances are, the person doing the setup gave up or said they'd come back and never did - - - maybe you get it figured out quickly, maybe you need a marine tech along with sea trial go swing the boat. This type of adjustment can become trial and error and get pretty expensive quickly - check the version of SW/firmware is current. All engine leaks - no matter how small - should be resolved with OEM parts.
The above said, brokers often nudge the sale along with as short a sea trial as possible, preferably to yard for haul and survey. Once in the yard, there is a tendency to try to nudge the buyer into keeping it on the hard for a bottom or minor repairs. Unless you know what you're doing and are comfortable with the vessel, best guidance is to splash the boat ASAP. Hoist is part of your sunk cost for survey and inspection. And it gives you time to mull over the data in front of you.