Bekhorot 28: Ethical Blemish-Checking

4 mishnayot! 1 - On determining that an animal has a blemish - after slaughtering, and the tension of having non-experts involved in determining whether the animal has a blemish. 2 - What if the kohen makes an error in judgement? What is done is done. But the judge may well be liable. With mention of dina de-garmi. 3 - A story (in the mishnah!) about the error of the previous mishnah. 4 - Making sure that one's salary was not contingent on the assessment of blemishes - unless the person checking was an expert.