Restaurants are probably the best example, especially when people are outrageous to the waiter, hostess, or barback when problems are clearly outside of their control (kitchen issues, staffing issues). Other good places to judge this characteristic: Taxi Cabs and customer-support calls (you dont need to be on the call, simply listening to the person will tell you enough).
Also, to be clear, that doesnt mean that people have to be doormats - just not a complete asshole. Empathy goes a long way.
I try to avoid doing business with people who fail this test - is usually means they are highly emotional / rash about decisions, or that they don't mind badgering other people to get their way. Both are bad.
Separately, though, I do think that the very concept of being made to deal with someone's personal secretary instead of the person themselves is a rude gesture by that person, because usually a personal secretary has no authority to help you with your problems. It's the same sort of rudeness implied by redirecting you five times to different departments on a support call, but immediately and in person. (Note that a receptionist in, e.g. a company lobby is a totally separate and useful thing; it is only when the receptionist has a one-to-one relationship with the number of people they route information to that it becomes a snub.)
At US companies--I can't speak to how things work in Japan--departmental admins/secretaries often wield an enormous amount of influence and can absolutely help or hurt you. A personal secretary almost always has the ability to help you if they choose to. Your attitude toward them can make a difference.
Bad idea.
I can't tell for sure, but what Jessica is most likely interpreting is sub-conscious gestural leakage. A fancy term meaning you exhibit both facial and gestural signs that can be read. For example if you are be probed to check for flexibility, a necessity in "fog of war" situations in Startups, and you exhibit a "fearful" or "sad" facial micro-expression ~ http://face.paulekman.com/aboutmett2.aspx this could be how Jessica is determining a flake. You can tell a person maybe showing certain emotions but you cannot be sure if they are "conscious" (lying) or "unconscious". Judgment is required. Conscious lying can also be masked by certain types of pharmaceuticals which can mask these feelings.
YCombinator could improve themselves in the selection process by getting better at recognising the fundamentals of faces, emotion and deception ~ http://www.paulekman.com/micros/ Naturals such as Jessica interpret but not fully understand the science of it meaning you can get false positives.