Peter spoke of a proverb in which, The dog is turned to his own vomit again; and the sow that was washed to her wallowing in the mire (2 Pet 2:22, see also Prov 26:11). Of note, our version of Proverbs is slightly different but Mormon quotes the same passage as Peter—which was apparently available to him in the brass plates of Laban.
The Nephites had stooped so low that similes of vomit eating dogs and wallowing swine seemed to be the most appropriate representations, especially since both could go from clean to dirty in such a short amount of time. Less than ten years prior, there was not a living soul among all the people of the Nephites who did doubt in the least the words of all the holy prophets (3 Nephi 5:1). Now there were but few righteous men among them (v. 7). Elsewhere, Mormon laments:
’…how quick to do iniquity, and how slow to do good, are the children of men; yea, how quick to hearken unto the words of the evil one, and to set their hearts upon the vain things of the world!
Yea, how quick to be lifted up in pride; yea, how quick to boast, and do all manner of that which is iniquity’ (Hel 12:4-5).