One of the things I immediately see when I show a house is the electrical system. I instinctively look at the wiring early in a walk-through because poor wiring can signal other things are not right with a home. On a recent electrical project my contacting company did, we found some of the most amazing, and dangerous, wiring I've seen in 40+ years in the field.
The former homeowner had done a lot of his own wiring. That alone is a great reason to have a home inspection. When someone tells me he has done a lot of the wiring, I get nervous. Once in a great while, it's awesome, but that really is the exception and not the norm. This particular project had splices on top of splices.
It took longer to untangle the various connections than it did to re-wire the entire series of circuits. How some of these homes don't burn down is a mystery. When you're looking at a home to purchase, have a reputable home inspector do an inspection before you start figuring out where to put your furniture. If there is one obvious electrical problem, be aware, there might be dozens hidden behind drywall, in crawl spaces and attics. This is an area that you never want to cut corners on.