A "Red Paint" Argument is, put simply, an argument that relies on irrational conclusions that no one in their right mind would honestly arrive at naturally. The eponymous example is that of someone being opposed to using a picture with blood in it for a page image because "people may mistake it for red paint", despite it obviously being blood.
Basically, if an argument requires you to completely ignore all context surrounding the subject — sometimes including parts of the subject itself — then it's probably a red paint argument.
This term mainly sees use in Image Pickin' discussions, but it can come up in the Trope Repair Shop as well.
