How can you quickly find out who you are dealing with?
By looking at their natural assumptions, keeping their environment in mind.
When people assume the worst about you, and ascribe negative intent when there is none, it says a lot more about them, their attitude towards others, and their mindset, than it says about you. It does not necessarily make them bad people - there may be different reasons for their reactions, it may be that they are working in an environment where they have made lots of bad experiences, or they may be going through a rough time, or they may, well, not be very nice people. The important thing to remember is, that very seldom does it have anything to do with you. Maybe you could have phrased your question or comment better, but if a person had assumed positive intent, a mis-phrased question or comment would have led to myrth and laughter, not to a bad reaction. Always remember that, and refrain from adopting somebody else's negativity into your life!
This is also a good way to gauge the health of a company's culture - how do people inside the company react to questions and comments, from each other and outsiders - do they automatically assume the worst even about innocent comments and actions, or do they try to see or try to find the beneficial intent behind it, even if they don't immediately understand it? Do they even ask for intent or just assume it? How do they react to an explanation? Can they see the humor in an odd question, or does it automatically become the trigger for a witch hunt?
Even if you are not thinking about working for said company, the answer to these questions will likely tell you a lot about their teams' and departments' ability to work together, and therefore their efficiency, their openness to innovation (which presupposes healthy curiosity), and their customer service.