While nudity is nearly always removed, violent videos involving assaults on children, racially charged hate speech and images of self-harm among underage users all remained on Facebook after being reported by users and reviewed by moderators.
It reveals violent content including graphic images and video of child abuse or assaults on children is allowed to remain on the site despite being flagged by users as inappropriate and requests for removal.
Facebook, the world's biggest social network with more than two billion users, called the practices "mistakes" which do not "reflect Facebook's policies or values".
An undercover reporter for Channel 4's Dispatches was told by a moderator at a Facebook training centre in Dublin: 'If you start censoring too much then people lose interest in the platform.
Dispatches showed that during training sessions, moderators were shown a video of an adult man punching and stamping on a toddler. "It's all about making money at the end of the day", an unnamed Facebook moderator allegedly told the filmmakers.
Retail representative body Retail Excellence has suspended its partnership with Facebook after the expose of practises and content moderation on the platform by a Channel 4 programme last night.
Facebook have removed the content since Channel 4's revelations.
Mr McNamee said: "It's the really extreme, really unsafe form of content that attracts the most highly engaged people on the platform".
Richard Allan, Facebook's vice president of public policy. However, he responded, "But I just don't agree that that is the experience that most people want and that's not the experience we are trying to deliver". Another meme showed a little girl being held underwater, with the caption "when your daughter's first crush is a little negro boy".
Facebook told Channel 4 that the image did, in fact, violate its hate speech policy, and that it was "reviewing what went wrong to prevent it happening again".
One such example was a comment that told Muslim immigrants to "f*ck off back to your own countries". "People come to Facebook for a safe, secure experience to share content with their family and friends", Allan said in a new documentary by the long-running investigative show, Dispatches, from the United Kingdom (UK).
The investigation also found that extremist pages which had a lot of followers would be treated with special consideration, in the same manner as pages for governments and large news organisations.
The lightning rod in this entire situation is United Kingdom far-right organisation Britain First, which was granted shielded review, and did not have any of its toxic content pulled, or indeed have their page banned.
Facebook also denied that it kept hate speech content online for profit.