For example, (and let's be fair and balanced here) we can go back in my recent memory to Richard "I am not a crook" Nixon. How do you define "crook"? Wasn't Watergate a break in and didn't segments of incriminating Oval Office audio tape vanish?
Bill Clinton's struggles, too, with American English are well documented. He was unsure of the words "is" and "sexual relations". Wonder how he would fare on "Are You Smarter Than a 5th Grader"? I'll bet they know what "sexual relations" are.
George W. Bush had a different understanding of the word "accomplished" (as in "mission accomplished") than the populace. We still don't have a clue as to where Osama Bin Ladin is hiding or how to get him. We do have modifiers in our language that could have helped such as, "somewhat" or "partially".
Our current President is confused over a word that we hope he would know well: "tax".
What is it about living in the White House that renders men with above average intelligence suddenly ignorant of simple words?