Adam Clarke on Jeremiah 48:11

Moab hath been at ease - The metaphor here is taken from the mode of preserving wines. They let them rest upon their lees for a considerable time, as this improves them both in strength and flavour; and when this is sufficiently done, they rack, or pour them off into other vessels. Moab had been very little molested by war since he was a nation; he had never gone out of his own land. Though some had been carried away by Shalmaneser forty years before this, he has had neither wars nor captivity.

Therefore his taste remained in him - Still carrying on the allusion to the curing of wines; by resting long upon the lees, the taste and smell are both improved. See the note on Isa 25:6.