Rust, water in oil, corrotion on electrical components.. Is winterization an issue? If so, check all hoses, bends and such. Both cooling and exhaust.
A lot of boats deteriorate due to not being used enough.. Imagine your car sitting there for 6 years, every rubber component would be hard and in need of change.
Apart from that, if it all seems ok and the hull looks good i wouldn't let it ruin a good deal