You may know a sheep from a swine, when both have fallen into the same mire and are, in fact, so bemired, that neither by coat nor color can the one be distinguished from the other. How then distinguish them? Nothing more easy!
The sheep is a type of the godly, strives and struggles to get out of the muck. But the swine, in circumstances agreeable to its nature, wallows in the filth.
[Thomas Guthrie]

2 Peter 2:22 … But it is happened unto them according to the true proverb, The dog is turned to his own vomit again; and the sow that was washed to her wallowing in the mire.
Matthew 7:15-16 ...Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves. Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?❤