The second hand opens up possibilities for those looking for products already used and for those who want to put back into circulation goods that they own. For a trader, however, convenience depends on activities that go beyond simply publishing an ad.
A used product must be identified, examined and described. Conditions, defects, possible interventions and availability of documentation affect the confidence of the buyer. For some categories, verifying authenticity requires specific skills and appropriate procedures; a safe description without sufficient verification can compromise the service.
Profitability should be assessed on the full path. Acquisition, control, cleaning, photography, storage, shipping, and demand management all absorb resources. A high margin between the purchase price and the sale price can be reduced when these activities are taken into account.
Environmentally, re-use is consistent with the focus on product durability in the European Textile Strategy. This does not prove that every single transaction has a net benefit: transportation, treatment and actual replacement of new purchases can change the outcome.
I propose to build the service from a few known categories, with clear criteria on accepted conditions and an accurate description of the products. The goal is to allow the customer to understand what he buys and the operator to measure the real cost of the labor needed to sell it.