Musar zu Wajikra 11:43

His food should be clean and he should not eat "royal dainties" but ordinary food and ordinary drink according to his means. He should not eat nor drink out of repugnant dishes lest he transgress the commandment: "You shall not draw abomination upon yourselves…" (Lev. 11:43), but everything shall be with cleanliness.

Our sages (Yoma 39a) have said on the verse (Vayikra 11:43): "And do not make yourselves unclean by [eating] them [sheratzim (creeping things)], that you be rendered unclean by them"— If one makes himself unclean a little, they make him unclean a lot; [if he makes himself unclean] in this world, they make him unclean in the world to come." Rashi explains there: "They permit him to become unclean a lot," but this does not accord with "they make him unclean."

And all of this was alluded to in the verse concerning Yehoshua ben Yehotzadak, the high-priest, viz. (Zechariah 3:1): "And He showed me Yehoshua the high-priest standing before the angel of the L-rd. And the Satan was standing on his right, to accuse him… (4) …Remove the dungy vestments from him [Yehoshua]." The "dungy vestments" connote the uncleanliness of transgressions, which are as repulsive as dung. And "Remove … from him" indicates that he was clothed in them against his will. And this is what Scripture tells us tersely in (Vayikra 11:43): "Do not make yourselves unclean in them, lest you become unclean through them."