Wikipedia:Source it

Over time, unreliable sources creep into Wikipedia. These may include personal websites, predatory open access journals, self-publishing and vanity press books and the like, or sources that are agreed, after debate at the reliable sources noticeboard, to be generally unreliable. In some cases there may be very large numbers of articles that use a specific group of unreliable sources as a reference (e.g. biographies citing the Daily Mail, which, as of 2019, is considered generally unreliable).

The process of removing these is time consuming and may be suitable for semi-automation. In many cases the source is the sole support for specific text. Different editors have, sometimes in the same discussion, asserted that:
 * 1) The text must be left and tagged with citation needed
 * 2) The text must be removed
 * 3) The text may be left if uncontroversial
 * 4) The editor removing the source must replace it with a better one

In practice, consensus is that any of the first three may be appropriate depending on context. An editor may make a reasonable judgment as to whether a piece of text is controversial or not, and may decide to leave it with no specific source, or to remove it, or to tag it as needing a citation.

The editor removing the source assumes some responsibility for the unsourced content, so #1 is the only truly clean approach in line with Wikipedia policy, but any other editor may choose to reintroduce the text (without the unreliable source) and take responsibility for it.

Assertion 4 does not have consensus. The onus is always on an editor seeking to include content, to provide a reliable source. As with 2 and 3, though, any editor is welcome to reintroduce the text with a better source if they can find it, or none if it is adequately supported elsewhere or is obviously correct and unchallenged.