What is the best workflow for a classified forum part ?
Eg when an item is sold/purchased/exchanged should it then be marked as “unlisted” or moved to a trash category?
Or are there plugins?
How to allow a user to unlist it ?
I’d probably use discourse-solved, so that sold items get marked with a checkbox.
And put a link to your Classifieds subforum to show only the unsolved topics, like https://meta.discourse.org/c/support?solved=no
Well, consider this plugin too:
A topic that has exhausted its function (article sold, changed or traded) can be archived by the seller (aka topic’s author).
My plugin archives the topic. I needed the topic to be searchable (for bulk actions) … unlisted (hidden) topics cant be searched.
So people would mark topics as sold/purchased/exchanged and category moderator would bulk-move them under archive category. The easiest way if you want topics to remain present but don’t want them to stay under trade category 
Any new functionality here in newer releases ? 
¡Me encantaría ver cualquier actualización aquí! ¿Alguien ha implementado con éxito una categoría Clasificada?
¿Definir clasificada?
¿Te refieres a una categoría privada? ¿Crear un grupo y solo darle acceso a ese grupo específico a la categoría?
Me refiero a un Clasificado en cuanto a un lugar donde se compran/venden/intercambian artículos, que es de lo que trata este tema.