If one finds a string of birds in the possession of a Kuti, there are various ways of increasing rigor to test whether the Kuti had done the slaughtering properly, each of which concludes with determining whether the Kuti himself would eat from his shechitah. That is, where they accepted the halakhic requirements, they were incredibly careful — and if they didn’t accept the requirement to begin with, then they weren’t trustworthy. Also, investigating Rava’s view on one who intentionally eats non-kosher food – and yet that person can be relied upon for his assessment of kashrut, and even if that person does idolatry. Plus, the human enticement of food and drink just won’t work for the Divine.

https://creators.spotify.com/pod/profile/talkingtalmud/episodes/Hullin-4-Can-We-Trust-Jezebels-Kashrut-e3irhgn