It is a bit subjective, but we can all agree that guardian.com is more reliable than clickhole.com
Here I define "reliability" as the tendency to publish information that are considered true by the majority of academics in the relevant field, and the tendency to not publish information that is later found to be erroneous.
Is there a database giving websites a reliability score?
The score could be decided by experts or rated by users or somehow generated (for instance by seeing how often the website is used in Wikipedia citations).
Sometimes very different publications are hosted under the same domain name, so it might make sense to have a finer granularity (by URL?) if needed.
The database should cover at least websites than market themselves as news websites or reference websites.
Such a database already exists here but it is not open data, and it is only available as a web interface or browser extensions, not available as a full download: http://www.lemonde.fr/verification/