Loaded question will get loaded answers.
It's like a high mileage car that has been well maintained. 200,000 miles on a car that was well cared for is still a good car. But a car that never got oil changes, tune ups or any repairs is a piece of junk at less than 100,000 miles.
If the boat you are looking at is covered with corrosion, spiderwebs, and generally dreadful to look at, you already have some idea of the neglect it got.
Not to say the pretty boats don't have their own problems. You can garage a boat into neglect as well. But there is a slightly higher survival rate.
Race boats usually are highly strung and run real hard - but also get regularly dismantled and tuned. Stock boats don't have a lot of knobs turned, but lend themselves to "if it ain't broke, then don't fix it".
Study the buyer's guide and ask these questions to find out what the boat has been through.
Of course, feel free to share your concerns with us. Tough to assess a "good deal" from thousands of miles away, but we'll try our best!