You probably paid an inspector to check out your house before you took
ownership, or made a purchase offer. For about the same money, you can hire
a surveyor to check out any boat you buy, before signing anything. Do it.

And, if you're buying from a dealer who also runs a marina, wander around
the docks and ask a few people how the service has been. Not the
dependability of the ice machine, but the mechanical service.