lit. so horrible that one cannot bear to look (idiom)
fig. miserable; horrendous; atrocious
Definitions (粵典–words.hk)
形容詞
非常淒慘、可怕,令人唔忍心睇到 too horrible to look at
海嘯發生之後嘅沙灘,滿佈屍體,真係慘不忍睹。
海啸发生之后嘅沙滩,满布尸体,真系惨不忍睹。
hoi2 siu6 faat3 sang1 zi1 hau6 ge3 saa1 taan1, mui5 bou3 si1 tai2, zan1 hai6 caam2 bat1 jan2 dou2. The beach after the tsunami is covered by corpses, it's just too horrible to look at.
Definitions (Wiktionary)
phrase, idiomatic, of people or situations
to be too horrible to look at