Hiring a contractor to do the inspection. Not hiring a full-time inspector. Not being present during the inspection. Looking for the lowest-priced inspection. Accepting wiring that isn't faulty, but is outdated.
Outdated wiring can make adding appliances very expensive.
It can make minor repairs confusing and potentially dangerous to a novice. Obsessing about the obvious, but less important things. A leaky faucet is relatively easy to fix. Slow-draining toilets and tubs could be a sign of problems bigger than clogs. Rejecting a house over a fixable problem, rather than asking the sellers to pay for the repair or lower the price.