"...black, but comely." refers to her status as an outdoor laborer. Her tanned skin was not the culturally popular concept of 'beauty.'
Nearby verse SS 1:4 kind of blows the alegory theory, btw.
An important principle in understanding God's Word is that it is spiritually discerned.
My message and my preaching were not with wise and persuasive words, but with a demonstration of the Spirit's power, so that your faith might not rest on men's wisdom, but on God's power.
We do, however, speak a message of wisdom among the mature, but not the wisdom of this age or of the rulers of this age, who are coming to nothing. No, we speak of God's secret wisdom, a wisdom that has been hidden and that God destined for our glory before time began. None of the rulers of this age understood it, for if they had, they would not have crucified the Lord of glory. However, as it is written: "No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him" but God has revealed it to us by his Spirit.
I Cor 2:4-10
Is there no poetry in your soul? God gave all of us both rational, linear mental abilities and non-rational imaginative mental abilities, and I firmly believe that we are meant to use both. To allow one to cancel out the other is to live an impoverished life.