Well, I don't know how appropos this is to this particular discussion but I will say it anyway. In Japanese custom at least, and this may or may not be true for Korean customs, a bow of respect is always given with your eyes averted and your head down. However, when preparing to fight the bow is altered to be able to watch your opponent. Looking at a person while bowing in polite company would be an insult and possibly a threat. As to being able to see their feet move, kicking you in the head while bent over doesn't require you to move your feet simply to kick quickly.