^They may not be "evil", but this story seems to be building to an "us vs. them" thing.
Even assuming so, Tellarites are ugly, and they'd be on the "us" side. I don't think its fair to say the "friendly" races are all beautiful and the antagonists all horrible in appearance. I don't think Star Trek has ever gone too far down that road, happily.
Anyway, I suppose its in the eye of the beholder a lot of the time anyway. I for one find Cardassians very attractive, some others find them displeasing.
