Dust, in Ezekiel 26:12, signifies the lowest things which are of the sensual principle of man. They can be either good or bad, depending on the context.

In Isaiah 40:12, the dust signifies exterior or natural truths and goods of heaven and the church.

In Genesis 2:7, the dust is good, and we see some interesting nuances:

First, there's this: 'To form the man, dust from the ground' is to form his external man, which had not previously been man... (Arcana Coelestia 94)

Here, this formation of our external body and mind is a precursor, setting the stage for God to "breathe into our nostrils".

In Arcana Coelestia 1610, we find this passage, where again, dust has a good signification:

'Dust of the earth' has regard to those things that are celestial, for, as shown already, 'the earth' means the celestial aspect of love; 'dust of the sea' has regard to those things that are spiritual, for 'the sea', as has also been shown, means the spiritual aspect of love; while 'as the stars of heaven' means both but in a higher degree. And because these things cannot be numbered they therefore became common expressions to describe growth and multiplication beyond measure.

Then, in Arcana Coelestia 3707, these ideas get pulled together:

The reason the dust of the earth symbolizes goodness is that the earth, [or land,] symbolizes the Lord’s kingdom and therefore goodness, as shown just above in §3705. The dust of that land, then, means goodness, but earthly goodness, since the land symbolizes what is lowest in the Lord’s kingdom....

But there are bad connotations, too. In Micah 7:14-17, licking dust symbolizes being only sensual - bodily and external, worldly, and selfish. It's much the same in Psalms 72:9, where "Barbarians will bow down before God, and His enemies lick the dust...". See Arcana Coelestia 249, 3413 for interesting explanations of this.

(Odkazy: Apocalypse Explained 1145)

3379. 'And I will give to your seed all these lands' means derivative Churches. This is clear from the meaning of 'seed' as truths, and so those who possess truths and are consequently called 'the sons of the kingdom', dealt with above in 3373, and from the meaning of 'lands' as rational concepts which, when enlightened from the Divine, are appearances of truth, also dealt with above, in 3368, and so those with rational concepts enlightened from the Divine, or what amounts to the same, those who dwell in heavenly light. Since none but those who are in the Lord's kingdom in the heavens, that is, in heaven, and those who are in the Lord's kingdom on earth, that is, in Churches, dwell in that heavenly light, it is evident that 'these lands' means Churches. For Churches are not Churches on account of their being called such and of their confessing the Lord's name, but on account of the good and truth of faith that exist in them. Good and truth of faith themselves are what make a Church, indeed they are the Church, for present within the good and truth of faith there is the Lord, and where the Lord is, there is the Church also.