I think regardless of whether we have a white list, black-list or both there will be sources that fall in the grey. Here’s an example. Imagine a school shooting in XYZ Community. Perhaps the local community newspaper provides a very detailed and credible article - the site is small enough it is unlikely to be on either a white list or a black list but it could still be a good contribution to the site. I providing examples of sources that are broadly accepted or not accepted is useful, but at the end of the day I think much of it falls to moderator discretion.