Originally Posted by CaptainMiles

Yes, I personally know of one such person, a close friend of mine. According to him (and I believe him, he is very honest) he did answer yes. He was summoned for an interview with the consul, who wanted to know the nature of his visit to the U.S. (academic conference), and asked why he answered affirmatively to that question, to which my friend say "because it's true". The consul was puzzled, saying "but you know, most people in your circumstances would not have answered yes". Anyway, my friend was issued a single-entry visa with a bunch of codes on it. Those codes prompted the inspector at the border to dig out his books and read a lot before admitting my friend. All went well with the visit. On the next visit, he applied again for a visa using the same process and again answered yes to the communist question, and was given an unlimited multiple-entry visa. They must have figured out he was no threat.

The same process probably still applies today to those who answer yes to intending to assassinate the President. Let them in once, and if they come back without having assassinated the President it's safe to let them back in as they must be either lying about their intentions or incompetent at the task.