Chabad on Kaparot

http://www.chabad.org/library/article_cdo/aid/407513/jewish/Kapparot-The-Chicken-Thing.htm

Money quote:

The practice of originally kapores created a certain amount of controversy amongst rabbinical scholars. The Ramban, also known as Nachmanides, who lived from 1195 to 1270 C.E. criticized it as a superstitious practice of the Emorites, one of the neighboring pagan peoples to Israel. Later, Rabbi Joseph Karo (1488 - 1575 CE) also criticized the practice in the Shulchan Aruch (Code of Jewish Law). While there have been communities that do not practice the custom, eventually most of the Rabbinical authorities did support it and encouraged its practice. As such, kapores is practiced by many in both Sephardic and Ashkenazic communities.

Has Orthodox Judaism ever endorsed such a practice with these words before? Do we not always swear that we are following the Shulchan Aruch? Is there a SINGLE OTHER CASE where the Shulchan Aruch openly criticizes a practice and vast swaths of Orthodox Jews do it anyway and refer to it as a "Mitzva"? I mean, granted the Rama disagrees based on gedolim that did it, but the Mechaber actually goes out of his way to denounce it and say why. (See O"H 605:1) This may be the only place where a sourceless practice is defended like this.

The article also mentions that the practice is not mentioned in the Talmud. Actually, it may well be referenced in Avodah Zarah Daf 14, Mishna 1:5

א,ה אלו דברים אסורין למכור לגויים--אצטרובלין, ובנות שוח בפטוטרותיהן, ולבונה, ותרנגול לבן. רבי יהודה אומר, מוכר הוא לו תרנגול לבן, בין התרנגולין; בזמן שהוא בפני עצמו, קוטע את אצבעו ומוכרו, שאין מקריבין חסר לעבודה זרה. ושאר כל הדברים--סתמן מותר, ופירושן אסור. רבי מאיר אומר, אף דקל טב וחצב ונקליבס, אסור למכור לגויים.

For the non-Hebrew speaking, the Mishna lists things that idol worshipers use that you are not allowed to sell to them, for fear of facilitating their foreign practice. One of those things, the bolded words, "A WHITE ROOSTER"!!!

It is most stunning.