In reference to the above quote by Inigo Montoya, most people do not understand the actual meaning of "ignorant". Funny enough, many people in this day and age are ignorant to the definition of the word. Unfortunately, "ignorant" is often used incorrectly in politically charged discussions where the user simply doesn't have anything smart or factual left to say, and is simply resulting to insults because he or she is offended by statements made by his or her opponent. In simple terms, the incorrect use of the word "ignorant" is a sign of weakness and an inability to sustain a factual, intelligent, and informed conversation.
Easy test is if you would like being called ignorant then it is not an insult. If being called ignorant has an emotional response like the vast majority of people would it is an insult. There is no context I know of where calling someone ignorant to their face would not be an insult. Trouble is we live in a world full of internet tough guys that hide behind their keyboards and call names.
For the most part, it's just a buzz word that is used by intellectually lazy people to dismiss the arguments of people who disagree with their points of view. The word can still have meaning, but people just use it mostly as an insult these days because they want to sidetrack the issues at hand.
The word ignorant has lost its significance over the years. People say it out of context and with anyone they disagree with. It was not always this way but people with a limited vocabulary can't find the words they want to use and just call people ignorant. Ironically, those that do this are ignorant in a way.
If someone is blatantly showing their lack of knowledge for a subject and wants to present an argument as factual bias, then ignorant is the right way to describe that person's statement. If I wanted to call someone stupid then I would use the word "stupid". Calling someone ignorant is actually being nice and allowing them to reflect on their faults without force.
People misunderstand the word and assume that ignorant is a synonym for stupid. It is not. Most people don't comprehend that ignorant means that they do not know the subject matter being discussed. If they do, they just need to address the argument back to the issue at hand instead of focusing on whether or not they were just called dumb.
Although the word "ignorant" is probably used more than is proper, it still has meaning in conversations. If someone is ignorant of issues, the word can be properly used to describe that type of condition. Overuse of the word can become, but with limited and proper usage, the problems will be less common.