If a person with protanopia/deuteranopia looks at a red flag, one sees green-ish flag.

when you want to liberate the working class (or if you have red-green color blindness)

A literal flag colored red, if you or the flag is moving towards the other so fast as to blueshift it to green.

Hating the democratic party of the United States. Without any other context you would assume they are a republican. But once they start critiquing marx and explaning how Trotsky’s permanent revolution is the only viable path forward you know they are good people.

Alternatively, if someone supports the dems no matter what, that is a red flag that should never be overlooked especially when they start rationalizing their perverted beliefs by name-dropping minorities out of the blue.