Going in and out of houses all the time, I frequently see situations where owners and rehabers have ignored the basic infrastructure of the house in favor of glitzy finish-out. I see old, multi-layer roofs on houses with recent granite counters and new wood-veneer floors. It makes me nutz.
Do you know the expression "lipstick on a pig"? All the hairbows and makeup in the world won't change the fact that they are being worn by a pig. Where it may make the pig a better party guest, it doesn't change the taste of the bacon at all.
I have been watching a bit of Canadian TV currently showing on HGTV, "Leave It To Bryan". The premise of the show is that people frequently don't see the very real structural problems present in their homes. They just focus on wanting some superficial change in the finishes. The "star" of the show, Bryan Baeumler, believes that our urban housing inventory is a ticking timebomb. On his show, homeowners are convinced that the key to happiness is some fairly superficial change such as converting a closet to a bathroom. Then they are shocked when Brian detects and decides to fix a really major structural problem such as water-logged basement walls. It really is a great show.
There are five basic structural systems for a house: foundation, roof, heating/cooling, electrical and plumbing. Usually if there are problems, those problems are obvious. And, even if those problems aren't immediately obvious to the average home owner or home buyer, they are obvious to anyone such as a home inspector or general contractor. As a home owner, if you don't have confidence in your ability to spot those problems, develop a relationship with a reliable handi-person or contractor. Have them come over periodically and look around for you. Ask them to see if there is anything they think should be investigated or fixed. Even if they don't find anything, pay them for their time. You are getting the benefit of their years of experience and insight. If they refuse to let you press folding green money into their hand as they are walking out the door, mail them a nice gift card to a local steak house. You want them to be motivated to come look at your house again in a year or two! The fact that they didn't find anything to fix tells you things about them as well as the house. You want to hang onto their business card.
Even if you are good at spotting things, you won't catch them all. Last weekend, we tore out some sheetrock in my condo. We discovered a small leak inside the walls. There was no way to have spotted that problem until it became a much bigger problem. That won't happen now because it has been fixed. The point I am trying to make is that even people with lots and lots of experience will periodically miss things. That is why home buyers really need to have a licensed home inspector come and check out the home they are buying. It is their job to spot situations that need to be investigated.