'Scarlet,' as in Genesis 38:28, signifies spiritual good.

In Isaiah 1:18, this signifies truth derived from good, or truth from a celestial origin, such as is the truth of the Word in its literal and natural sense

'Scarlet,' in Revelation 17:3, signifies truth from a heavenly origin, such as is the truth of the Word in the sense of the letter or natural sense, which is meant by what is holy in it. 

(Verweise: Apocalypse Explained 67)

3339. In the next life those forms of light, and also those forms of warmth, manifest themselves visually. Angels live within the light of heaven and also within the warmth that has been spoken of. From that light they receive intelligence, and from that warmth the affection for good. Indeed the forms of light seen with their external sight have their origin in the Lord's Divine wisdom, and the forms of warmth which are also felt by them have their origin in the Lord's Divine love. To the extent therefore that spirits and angels possess intelligence in truth and affection for good they are closer to the Lord.