1783: New Uses for the Agentive -er Nov 1, 2019
Following from yesterday, there are plenty of English nouns which cannot be verbalized, including 'fact' and 'truth'. It would even be ungrammatical to add the agentive suffix '-er'. Even though this would be conceptually fine, it just doesn't really occur. However, informal usages have emerged for 'truther' (not 'facter' though) to mean 'believer in a conspiracy theory', such as '9/11 truther', in a similar pattern to 'flat-earther'. Indeed, you can see in this comedic exchange from "Drake and Josh" that 'truther' on the pattern of 'liar' is possible.
Be a Word Facter at patreon.com/wordfacts where this idea is explored further.