If this parable was about pottery and its uses, and this forum not about Hermeneutics, we could have a most interesting conversations about uses of pottery and what was honorable or dishonorable. However, since this forums is Biblical Hermeneutics and not Pottery, I'm going to assume you're asking about the meaning of the parable. Letting the bible interpret the bible:
Q. Generally, who is the potter and who is the clay?
A. The potter is YHWH and the clay are people of specific nations.
Isaiah 64:8 - shows that that Israel is the clay in this parable and YHWH is the potter: But now, O Lord, you are our Father; we are the clay, and you are our potter; we are all the work of your hand.
A. God formed mankind from the earth (Gen 2:7) so we are as clay to Him.
Job 10:9 - Remember that you have made me like clay; and will you return me to the dust? asks Job who was basically asking the potter what type of vessel he was and what the potter intended to do with him.
Job 33:6 - Behold, I am toward God as you are; I too was pinched off from a piece of clay.
Israel in rebellion confronted God on his judgements. See what Isaiah says in reply:
Isa 29:16 - Shall the potter (YHWH) be regarded as the clay (Israel), that the thing made should say of its maker,“He did not make me”; or the thing formed say of him who formed it, “He has no understanding”?
Isa 45:9 - Woe to him who strives with him who formed him,
a pot among earthen pots! Does the clay say to him who forms it, ‘What are you making?’ or ‘Your work has no handles’?
So there is little doubt how YHWH see his people. The question then becomes can the potter re-work his creation if he isn't happy with its use? Again, the bible answers this in YHWH's instructions to Jeremiah, specifically how he should prophecy:
Jer 18:1-10 - The word that came to Jeremiah from the Lord: “Arise, and go down to the potter's house, and there I will let you hear my words.” So I went down to the potter's house, and there he was working at his wheel. And the vessel he was making of clay was spoiled in the potter's hand, and he reworked it into another vessel, as it seemed good to the potter to do.
Then the word of the Lord came to me: “O house of Israel, can I not do with you as this potter has done? declares the Lord. Behold, like the clay in the potter's hand, so are you in my hand, O house of Israel. If at any time I declare concerning a nation or a kingdom, that I will pluck up and break down and destroy it, and if that nation, concerning which I have spoken, turns from its evil, I will relent of the disaster that I intended to do to it.
And if at any time I declare concerning a nation or a kingdom that I will build and plant it, and if it does evil in my sight, not listening to my voice, then I will relent of the good that I had intended to do to it.
The point is that if YHWH, says these faithless people (the work of his hands) are 'dishonorable' whereas those faithful people are 'honorable', that is YHWH's prerogative as potter.
Q. Why should we discuss 'people' (the thing signified) in this question, rather than 'pottery' (the sign)?
A. Because prophecy uses the same metaphors to convey information about YHWH's intentions with respect to faithful and faithless nations. Read Dan 2:41-43 now and understand that the empire that would consume Israel was being spoken about (since the Iron was Rome and Israel the clay).