Did al-Bukhari and Muslim always follow their so called conditions?

In my answer on https://islam.stackexchange.com/questions/7864/what-are-the-terms-of-that-which-has-reached-tawatur I've tried to address the topic of the conditions of al.-Bukhari and Muslim. I've also posted a related question: https://islam.stackexchange.com/questions/45275/what-exactly-are-the-conditions-of-al-bukhari-and-muslim I'm certainly not a scholar nor do I have deep knowledge in 'ulum al-Hadith. But I suppose that the conditions of al-Bukhari and Muslim must either have been quoted by both in some of their books (not necessary in the books known as the sahihs ... the correct full title of what is known as sahih al-Bukhai is quoted in my answer here https://islam.stackexchange.com/questions/2419/is-sahih-al-bukhari-considered-as-100-authentic-by-sunni-scholars) . Or later scholars have deduced them I strongly believe they were quoted by al-Bukhari and Muslim themselves. But as I know that both of them have quoted ahadith of da'if narrators I'd like to know whether they always followed their own condition in their major works (I suppose all consider the both sahihs as such, as I'm at least aware of many other works of al-Bukhari) or did it occur that they added or quoted a hadith which doesn't follow their own conditions? (Is it possible to explain why?) If so are these ahadith known, and what is their amount?