Shmuel teaches that if a slaughterer messes up and treifs up the animal, he is responsible whether or not he did it for free or for pay. Rabbi Yochanan disagrees and distinguishes between one who gets paid and one who does it for free. He compares it to laws of shomrim and just as one who gets paid to watch an item assumes more responsibility in the event of theft or loss, likewise by the slaughterer or any professional. However if they are not getting paid, they are like a shomer who watches the item for free who is not obligated in a case of theft or loss. Is a professional damaging an item more similar to laws of shomrim because the item was given to him by the owner? Or is it more like adam hamazik – a person who damages another’s item, in which case he is obligated even for unintentional damage (ones). Cases relating to a money changer are brought – where one rules on the validity of a coin and causes a loss. If he is a real professional, then he is not responsible if he gave the advice for free, however Rabbi Chiya ruled for himself beyonf the letter of the law and reimbursed a woman for her loss based on his ruling. A case ensues with Rabbi Elazar and Reish Lakish and the commentaries differ on whether Rabbi Elazar was an expert or not, thereby affecting the conclusion one can assume from that case. The mishna discusses more cases where the dyer did something different from what he was meant to do and there are 2 different cases and different opinions about what the halacha is in one of them.