As far as Song of Solomon, the dirty talk did not happen until they were married. Before \the marriage, it was clean. Correct me (with proof) if I am mistaken.
I am boggled, flat out floored that people could justify this.
1) Christ is not, never has been and never will be relative to each individual. Sin is sin. You are either glorifying our great God and King or you are not. Therefore there is a definite answer to whether dirty talking, as the action is sin or not.
2) Because there are some who ignore the numerous Scripture about acceptable talk/ words/ speaking, etc. and the numerous Scripture about sexual relations/ immorality outside of marriage; why don't we look at it from another point of Scripture. We can consider this in the group of things that are potentially sinful, yet Scripture does not specifically target them (which is most sin).
Do not cause your brother to fall.
9Be careful, however, that the exercise of your freedom does not become a stumbling block to the weak. 10For if anyone with a weak conscience sees you who have this knowledge eating in an idol's temple, won't he be emboldened to eat what has been sacrificed to idols? 11So this weak brother, for whom Christ died, is destroyed by your knowledge. 12When you sin against your brothers in this way and wound their weak conscience, you sin against Christ. 13Therefore, if what I eat causes my brother to fall into sin, I will never eat meat again, so that I will not cause him to fall.
Unless you are dating someone who is not attracted to you, it is highly, highly, highly likely that dirty talk will make him lust after you. And you are not married. Justify it all you want, distort what Jesus said all you want, you are in the end idolizing "dirty" talk by not giving it up to God.
Matthew 5:28
28But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart.
Everyone in the Greek, means everyone. Not just married men looking at other women, but everyone. Unless you are dating someone who is not attracted to you, it is highly, highly, highly likely that dirty talk will make him think with lustful intent of you. And even if you get married later he has still stumbled.
Let me draw it out more for you, how even desire before marriage, in the way it is meant only for marriage, is lust.
Say you justify your actions by saying you will get married soon (even 2 days from now). But tomorrow, you are walking down the street and a giant toad bites you and you die instantly. Bam! You were never married. It was lust and sexually immoral. And both of you would be held accountable (luck for you Christ atones for your sins).
Not only did you cause someone you love dearly (hypothetically -->) to fall, but your unwholesome comments (which are completely unneeded if you are as strong as you claim) were damaging to your own spirit.
Any guy who claims they can think naked thoughts and not lust is either a liar or Jesus. I am a guy, I have several guy friends, and this is a very common discussion among guys (that is sexual immorality). We cannot handle it. Why do you think Paul says it is better to marry than to burn with sexual desire to men? Because we do!
I'm trying to figure out what wholesome dirty talk would sound like. 
