Esav's Questionable Shechita
Rashi, commenting on Bereishis 26:34, states that Esav snatched women from their husbands and raped them for the first forty years of his life. In the next verse (26:35), Rashi comments that Esav and his wives worshiped idols; a source of great distress to Yitzchak and Rivka.
In Bereishis 27:3, Yitzchak instructs Esav to sharpen his sword and go out to the field to catch game for him to eat. Bereishis Rabbah 65:13 notes that the reason why Yitzchak asked Esav to sharpen his sword was because a blade with an imperfection is unfit to use for slaughter.
While Yitzchak did not eat the food that Esav slaughtered on this occurrence, the Torah tells us that on an earlier occasion (Bereishis 25:28) that Yitzchak loved Esav "because his game was in his [Yitzchak's] mouth". - thus seemingly implying that Yitzchak ate the meat Esav slaughtered.
Since we know that Yitzchak Avinu was a man of great spiritual sensitivity, how could he eat meat slaughtered by someone like Esav?