What Guys Said 1
I will tell you that it is because he is shy and afraid of looking at you and saying something that you may either take as wrong or that you may feel a little hurt by. I am telling this from my own personal lifes p.o.v.
What Girls Said 1
The dude probably likes you. point blank. When he looks down, imitate him and look down too. I know its seems stupid but sometimes it works to get him more comfortable. maybe eventually he will look you in the eye gradually. as far as the ugly thing goes, I don't think you have anything to worry about in that department.