That I don't have a problem with myself since there are words that are big but more accurately describe something to another person with reasonable cognitive abilities. Example might be planned obsolescence when you have to talk about the particular lifespan of an item. Instead of going into some large description to explain an item's particular longevity you can just say planned obsolescence within X time frame.
Only thing that irks me is when a person uses big words to talk down to others and make them feel inferior.
*Crap video I know* http://www.youtube.com/watch?v=QguWdSsI8S8sums up my opinion about idiots and big words. They hear it, think it is important, and use it as much as possible to make themselves seem intelligent as possible.
Forget the name of the forum goer that has it in their signature, and the exact quote, but I think it goes, "Light travels faster than sound, this is why people seem bright before they open their mouth."