Well yes it's offensive because it's not polite to say that anyone nonetheless an entire race of people are "butt ugly" whether you or someone else think they are or not.
Not to mention just because one person isn't attractive doesn't make it apply to everyone else that falls under that category. There are attractive as well as unattractive people in every race, ethnicity, and nationally.
No, it is either a universal truth or a personal opinion. America is established upon the freedom of speech, even those which may be wrong, not the political correctness, which uses "hate speech" to stop people from saying what they think.