Per Washington State Standard of Practice, your home inspector is obligated to remove the cover from the electrical panel. This was a point of contention early in the standards-writing process and electrical contractors in particular argued against it.
Common sense prevailed and home inspectors remove covers. This is a necessary part of the inspection. Just in the last few days, I've seen a panel where the plastic was literally melting. (Yes, we turned off the power, notified the agent, and thanked our lucky stars the home didn't burn down the day before.)
We look for a variety of issues on the interior and I'll hit those in later posts and videos - though if you have a specific question, send it along and I'll move it up the queue.
One caveat - we are required to remove 'readily accessible' covers. If the panel is buried under behind a 700 lb. gun safe, I'm not inspecting it. Likewise, I add the very sensible (to me) proviso that if I test the panel and it lights me up, I'm not going further and trying to remove the cover. In either case, your inspector is obliged to tell you that he did not remove the cover and why.