Can you point to any instance where WikiLeaks has released information that was not authentic and correct?
see http://www.mediaite.com/online/julian-assange-hillary-clinto...
and similar
These were not just random samplings. They were cherry-picked from a huge collection and delivered with perfect timing. This is agency work, not Assange.
Also, while I doubt they've ever released fake documents as part of a leak, they do often push incorrect and/or unverified theories and ideas on Twitter.