In general, Shi'as do not believe in the concept of a completely authenthic - or sahih - book of hadith as a whole. Specifically with regard to the sihah sitta which our Sunni brothers believe in, our position is the same. We do not believe any book of hadith is 100% accurate.
Moreover, we do not also partially accept them and they are, more or less, completely rejected in terms of their authority to act as a hujjah or proof on a Shi'a. That is to say, if one of these books has a specific narration of event recorded in it, which for example say X is wajib, we would not be obligated to do X action. We may look at them as auxiliary sources of information in providing a historical context of the era or as a tool in our discussion with Sunnis but they are not binding proof for us personally. We may also choose to accept something recorded in them if it corresponds with our own texts and does not contradict them or the Qur'an.
There are several reasons for this. The first and foremost is the intellectual argument, which necessitates caution when faced with a supposition that a book compiled and collected by a human is 100% accurate. Only the Qur'an can be found to be true to that standard and even that is only due to Allah (SWT)'s own promise that He will protect His Word.
The second is ilm al rijal as Sunni narrators of hadith are obviously looked at with a certain degree of scrutiny by Shi'a scholars - and the same is true of Shi'a narrators among Sunni scholarship for the most part. Then, there are people like Abu Hurayrah, who is one of the principle narrators of a book like Sahih Bukhari and whose narrations comprised, if I'm not mistaken, 1/3 of that book but there are narrations within the sihah sitta themselves which raise doubts about his credibility, with Aisha calling him a liar. As such, one cannot trust the word of such a man and if a book is largely comprised of narrations by such a man, then it is logically imperative upon us to also treat such a book with a great degree of caution and suspicion.
Lastly, we don't, as I've mentioned before, subscribe to the idea of a sahih book in general. We also have compilations of hadith that are revered above others, and some of these were also written by their authors with the intention of only containing the most reliable of narrations, but Shi'i scholarship in general has rejected the notion of a man-made book being completely devoid of flaw. Even if the author had set out with that intention, and was an individual of great standing, his own personal belief regarding the accuracy of his creation is not an authoritiatve proof upon subsequent generations of scholars. Thus, we accept neither sahih books from the Sunnis nor from the Shi'as. All narrations should generally be checked individually for their chain in order to determine the likelihood of their veracity.