Not knowing that the capital of Sweden is Stockholm doesn't affect your intelligence the slightest. You just don't know that datum. Nonsense or not, it's a phenomenon you must take into account when dealing with prospects. You need to go by the rules that are in effect out there. And the rule here is that if you say something your prospect does not understand, he will feel stupid.
People often use knowledge as a weapon of sorts.
Basically, all you have to do is talk knowingly about something the other person has little or now knowledge about. But it can also happen inadvertantly to experts. Your own danger zone is of course your area of expertise. But you can see that this is NOT the route to convincing your prospect of your own CPA skills. It is safe to assume most business owners don't understand much about accounting.