Exactly, if he opponent is 20m away from you and you run 2 hours towards him something is wrong, lol. Jokes aside, you obviously use your hearing as well. If the opponent already tricked you then he will continue to move and do something, either way there's plenty of clues you can use to free yourself.This one is a 'special' one. Not really a battle useful technique but it can find its purposes in our NW, as you have already mentioned yourself. An exceedingly simple technique, but most tend to misunderstand or over-complicate it. Since the Genjutsu will cause them to see themselves continuing on in this straight line path, when in reality they're running around in circles, I would say that I am going to put this one in the group of Trickery, since it basically tricks you and makes you see or believe something that isn't real.
Now that I think about it, usually its better to avoid this Genjutsu entirely by simply running in a non-linear path (e.g. a zigzag motion). However, if I do happen to be caught in it, I could simply use the reasoning, that as I believe that I am traveling in a straight line, but really in reality I am going in circles, I will soon enough begin to realize that I am not getting any closer to my enemy(ies) or target(s). Likewise there is one more way, by using thrown objects to decipher that I am moving in circles, since more likely than not the object will go off on angled flight path, clearly showing you're not moving in a straight line. I think I have seen that technique being used in a fight so I am aware of what it can possibly do.
Once I explained why I think it is a Genjutsu I would release myself from it with, for example a full body surge.
( Genjutsu: Jinmon ) - Illusion Technique: Interrogation
Rank: C
Type: Supplementary
Range: Short
Chakra Cost:15
Damage Points:30
Description: The user of this technique, upon casting on a stationary opponent with physical contact with them, is able to convince the enemy to give away information. However, this will only work on ninja two ranks lower and below than the caster.
Oh well, not really useful in my opinion. If you had a non-NW fight with someone you could force him to tell you his KG and stuff like that, but why go through the trouble of that instead of just finding it out the old fashioned way, by fighting. Sooner or later when the opponent finds himself in a bad situation he will resort to his hidden abilities and that's when you get to know who you're fighting so there's no use for this technique. And on top of that it works only against much weaker opponents.