If we're being honest here there are very, very few people who are in shape and take care of themselves that are still anywhere close to being able to be considered "ugly bastard". It takes some extreme fuckery to get people below "below average" in those cases. And it's usually extremities at that point. Wonky, huge ears or nose, lack of a chin or an obscenely giant one, etc.
I agree!
In anime usually the ugly bastard is like fat and wears glasses, and that's like a basic normal dude for the most part. But I guess when your characters are chiseled perfect and weigh 120 pounds for the men and made of slender goodness, implying someone looks "like an American" is kind of its own jab. Double so when they call it an ugly bastard.
You got to start getting into mutations and deformities or bad hygiene or stupidly old when it starts getting ugly and too far to want to think about sexually.
I'm sure there's people out there who like that though but I'll leave that to them. For me the ugly bastard kind of stops once they stop looking like an overweight 40-something, which seems like the vast majority of them tend to be.
Also there should be some kind of separation for old bastard, fat bastard, and ugly bastard. Ugly just is a catch all for too much stuff!