If one is living in a co-op and is not paying their dues as they are obligated to do on a regular basis in order to maintain the place, the Vaad, the management, is allowed to publicize on a notice board in the lobby area or in a similar place who is not paying and how much they owe. This is not Loshon Horo and is not considered humiliating someone in public, because it is a correct and proper procedure needed to maintain the place appropriately for the benefit of all the owners. If someone is going through financial difficulty, they should speak with the management and agree to an arrangement instead of ignoring their co-op dues which affects all the other owners as well.