Verse 6 states two imagined conditions which are concluded in verse 7, and so the two verses should be considered together.
Though his height mount up to the heavens: some interpreters see verse 6 as alluding to a tree, but this is largely imagination. It seems better to take it as referring to the man’s physical height or stature, and it can be expressed “He may be so tall he reaches the sky” or “Even if he is so tall he reaches the heavens.”
And his head reach to the clouds: the significance of the wicked being so high is only made clear in verse 7, where he is brought down to the level of his excrement. This line may be rendered, for example, “and he is so tall his head touches the clouds” or “and he is as tall as the clouds are high in the sky.”
He will perish for ever like his own dung: interpreters find numerous ways to avoid like his own dung, which is considered crude. Syriac has “like a whirlwind,” and Dhorme associates the Hebrew word dung with Assyrian and Greek and gets “like a ghost he vanishes for ever.” New Jerusalem Bible follows this, “but he vanishes like a phantom, once for all.” Some scholars understand dung to refer to piles of animal manure stored and dried for use in making fire. New American Bible accepts this: “yet he perishes for ever like the fuel of his fire.” The most likely idea is that he is compared to dung which returns to the soil and so disappears. Bible en français courant “He will end up like his own excrement.” Translators must be sensitive to public reading and should avoid an expression which will provoke amusement or disgust in handling this line. If the reference to his own dung is inappropriate or subject to conflicting interpretations, it will be better to follow one of the suggested interpretations. The point is that he will vanish, disappear forever; and therefore many other similes will convey this, or we may follow Good News Translation “be blown away like dust.” For languages which do not use the passive, it may be necessary to say, for example, “he will disappear like dust” or “the wind will blow him away like dust.”
He will so completely disappear that those who have seen him will say, ‘Where is he?’ Revised Standard Version makes the question direct and places it in quotation marks. Good News Translation makes it indirect. The question “Where is he?” is asked the first time in Job’s speech in 14.10. Verse 7 is similarly expressed in Psalm 37.35-36.
Quoted with permission from Reyburn, Wiliam. A Handbook on Job. (UBS Helps for Translators). New York: UBS, 1992. For this and other handbooks for translators see here .