It is well-known (among Sunni muslims) that Imam Bukhari was extremely diligent while collecting ahadith, and his criteria are considered among the most stringent (if not the most stringent) in the field of ilm-ul-hadith.
One of the criteria is that every narrator in the isnad is considered reliable. My question in particular is about whether or not a narrator — the one who narrated to Bukhari directly or any of the previous narrators in the isnad — was considered reliable if he was otherwise known to narrate fabricated ahadith.
I'm not asking if (nor implying that) any of the ahadith in Bukhari's Sahih are in any way fabricated. I am also not asking about whether any narrator fabricated these ahadith himself, nor those who transmitted a hadith knowing it was fabricated; such blatant fraud, when discovered, would obviously be grounds for dismissal by any reasonable standard.
I am referring particularly to the reliability of narrators who, without knowledge, continued the transmission of (or had at some point transmitted) a fabricated hadith from a (presumably) reliable source.
Was this concern one of the criteria used by Imam Bukhari in the compilation of his famous Sahih? Or, to put it another way, are any of the narrators in Sahih Bukhari known to have inadvertently transmitted a fabricated hadith otherwise?