Steatopygous asses

I happened upon this phrase in a book excerpt in a recent Speak Up issue. The translation given in the box with difficult terms on the right was bundas arrebitadas. Since I'd never seen the word steatopygous, though I knew pygous was related to buttocks as I knew the word callipygous/callipygian, I didn't dispute it, but when I got home, I checked my dictionaries and found the meaning of steatopygous. In Portuguese the word arrebitado means turned up, as a nariz arrebitado, a turned up/snub nose, and has an appreciative connotation when referring to posteriors, which steatopygous doesn't.

But I also have a problem with the phrase steatopygous asses in English. According to the dictionary, steatopygous means extreme accumulation of fat on and about the buttocks, esp. of women, thus the word should only describe people, not asses themselves.