This is an update to a former post that you can check out here. The previous post described the use of the term 「不恥」(bu4chi3) in a short story by a Taiwanese author. I later came across the term again in 《馬橋詞典》 (A Dictionary of Maqiao), a book written by a mainland Chinese author:

The phrase containing it in Chinese reads:

（二）三耳朵做過很多人所不恥的惡行[……]

(2) Sanerduo had done some pretty despicable things[…]

This appears to have the same counter-intuitive meaning as the text by the Taiwanese author, in which 「不恥」 (lit. not shame) means to consider shameful. I briefly considered the idea of “shameless” in English, or 「不知羞恥」 (to not know shame), but the subject of 「不恥」 seems to be 「很多人」 not 「三耳朵」.

This suggests that the use of 「不恥」 in place of its homonym「不齒」, which means “to be ashamed to be associated with”:

This could suggest that in both mainland China and Taiwan 「不恥」 and 「不齒」 are used to indicate the same thing. The only possible caveat to this is that the copy of the book that I read was a 2011 traditional character version and this may not have been the case in the 1997 simplified Chinese original. Anyone got their hands on a simplified Chinese version?