The braided lines and angle stops connecting toilets, sinks, and appliances are not interesting components. They're also a common failure point, and when one lets go it does so at full line pressure while you're at work.
We check accessible supply connections, washing machine hoses, dishwasher and disposal connections, and shutoff valves for corrosion, wear, and visible leakage. Gas line connections get a leak inspection too.
One more thing, and it's free: know where your main water shutoff is and make sure it actually turns. The middle of an emergency is a bad time to discover the valve is seized. If yours is stuck, that's worth fixing on a calm Tuesday.