It's hard to buy a "Yacht"

I have been looking for about a year for a used liveaboard around 50' or less. There are lots of nice pictures, but when I start asking questions, it seems like some of the people that listed the boats act like it a big problem for them to provide info. I can ask 3 or 4 questions and maybe I get a text back that half answers one of the questions. And that's it. I scheduled to go see a boat recently and got the hull number and ran it. Boat had been on fire and it was not mentioned. Dang! Another one, "Oh yeah the generator doesn't work and one engine needs rebuilt".
If I find one that I like, I look at as many reviews that I can find on that model. Most mention problems with engines and rot in areas that seem like it would cost a fortune to fix. But they are still running and traveling after 40 years. Do surveyors actually catch the wood rotted areas that are glassed in? I am going to look at a 46' this week. The engine room pictures look great. I haven't seen an engine room that clean and neat in a well used boat in a long time. Hope the rest is good.
If the Detroit diesel engine hours are low (871) and they haven't been rebuilt ---ever, is that a red flag? Turbo's are newish. I don't know that they have never been rebuilt, just a question.
It will be used for short trips and live aboard.
Regards,
David