Connect the thought in these two verses (Jeremiah 48:11; Zephaniah 1:12) with the Laodicean's evaluation of himself and what we know about his relationship with God. He says he needs nothing, and he has settled on his lees. We also see Christ's reaction: It angered Him greatly.
The lees are the sediment that forms during the fermentation of grapes. They eventually sink to the bottom where they harden. Metaphorically, "settled on their lees" indicates floating, taking it easy, and having a very leisurely, casual approach to life. In the actual wine vat, the lees harden in due course, and they then picture an unacceptable, "hardened" lifestyle. A person who is "settled on his lees" is one who, through spiritual idleness and ease, has gradually become morally indifferent, tolerant of his lack of spiritual drive, and ultimately hardened to God and sin. In the process, he becomes blind to his spiritual state.
Zephaniah 1:12 goes on to say that one who is settled on his lees has reasoned himself into what amounts to practical atheism. He is saying by his conduct that God is not really governing or judging and that there will be neither reward for obedience nor punishment from sin. How far from God this person is! Thus, he gives himself over to his pleasures.
A Laodicean is a person straddling the proverbial fence. He has saving knowledge of God, but he is attached to the world and afraid to let go. He has deceived himself into thinking that he has found the perfect balance. He is convinced that he has the best of both worlds.