You don't understand polling. If you are going to ask people to place themselves on a scale, the people you ask must understand the categories. If you use categories not easily understood by the majority you have a useless question. Now there are sophisticated polling that ask a series of questions to affix people in whatever categories you want to use. These of course are better than asking people to self-identify because most people don't like to be seen on the extremes and may fear persecution (whether accurate or not) if they self identify in certain ways. The prime example is polling on drug use done by schools. What student is going to admit doing illegal substances to a institution that could cause them harm.