Ignorance is nothing to be ashamed of, in fact I will happily state I am ignorant of many economic principles. However, to combat that I am trying to learn more about them. In the same way the ignorant person is going on line asking questions as they really do not know.
On the other hand the troll. Is just out to raise your blood pressure and get you punching a hole in your computer screen.
But here is the problem the following question could come from any of these three people.
Why are there still monkeys if humans evolved from monkeys?
The only way I have been able to discern sometimes who is trolling, ignorant or lying is if I have met the person before on a forum or comment thread. This is why I will sometimes engage even the most randomly absurd question from a commenter.
What do you do to determine who is trolling, who is ignorant and who is a liar?